


Continuity

by orphan_account



Category: Undertale (Video Game)
Genre: ASL Frisk, Angst, Chara (Undertale) - Freeform, Character Death, Eventual Smut, F/F, F/M, Frisk has they/them pronouns, Frisk is not your character, Genocide Run, Grey!W.D. Gaster, Growling!Sans, Heterosexual Sex, Human has magic, Hurt/Comfort, Language, Magical appendages, Mating Cycles/In Heat, My First Undertale Fanfic, Post-Traumatic Stress Disorder - PTSD, Pregnancy, Racism, Sensitive bones, Soul Magic, Switch in Point of View, gender neutral frisk, gene splicing, human/monster experimentation, possible additions in the future - Freeform, reader is female
Language: English
Status: Completed
Published: 2015-12-17
Updated: 2016-01-09
Packaged: 2018-05-07 07:34:41
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 28
Words: 39,219
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5448434
Author URL: https://archiveofourown.org/users/orphan_account/pseuds/orphan_account
Summary: <blockquote class="userstuff">
              <p>Time lines were always the same, predictable when Frisk falls to the Underground.  It either ended with everyone living, about to pass through the barrier or with his own death in the Hall of Judgement.  Upon visiting W.D. Gaster's old lab, Sans discovers a door that has never, ever been there before.  He digs up some old research notes and finds the thing that he has never known he had been missing.</p>
            </blockquote>





	1. Chapter One

~~~~~~~~~~~~~~  
(First chapter is in third person Sans, switches to reader's POV in the next chapter)  
~~~~~~~~~~~~~~

"SANS, YOU LAZYBONES! GET OUT OF BED, WE NEED TO RE CALIBRATE OUR PUZZLES!" Came the nasally and scolding loud voice of his younger brother and Sans the skeleton's eye sockets slowly opened, the white lights that served as his visible pupils dim. His ever grinning mouth was slanted downwards in a frown as the skeleton tried to piece himself together for yet another timeline, trying to keep his bones from shuddering in remembrance of Frisk's sometimes innocent features flashing in triumph as his body crumbled to dust.

He adored his younger brother more than anything in this world, but that exact phrase was the thing that reminded him that everything had been reset. That he had to live through all of this again. Trembling, the whites grew a little stronger as the short skeleton sat up in bed, staring at his phalanges as he slowly came to grips that he was doing this...again.

It was hard to care and even when he did... It was useless.

"SANS!?! ARE YOU STILL SLEEPING??" Papyrus called loudly through the door and Sans took one more moment to steel his resolve.

"i am up, bro. don't wait up for me." Sans prided himself that his deep voice echoed without the distress and emotions he was being wreaked by.

"IF YOU AREN'T AT YOUR STATION IN HALF AN HOUR, I SWEAR I WILL DRAG YOU THERE MYSELF! I, THE GREAT PAPYRUS, MUST MAKE SURE MY BROTHER DOES HIS DUTY!" Sans could picture the flourish his taller skeleton brother pulled before leaving the house.

Once he was certain that he was alone, Sans allowed liquid to pool in his eye sockets and trail down his face. He had used to be angry when he found himself at the beginning of yet another time line, using his magic to trash his room. But hopelessness had set in after so many times and all Sans allowed himself was silent tears.

After a few minutes, the short skeleton pulled himself together. Sans had one day before Frisk left the Ruins and he had made it a tradition of sorts to return to W.D. Gaster's lab for reflection before he had to watch the human child's every move. Granted, there were only so many variations that occurred, but if it leaned more towards LOVE in Frisk, Sans had to prepare to hold the human off if only for his own peace of mind.

His left socket flared a brief bright teal before he teleported directly to the lab. Shoving his skeletal hands in the pockets of his blue parka, Sans let out a sigh as he viewed the broken down remnants of his 'home' earlier in his life. Papyrus didn't remember ever living here, as he had been too young. Sans was infinitely grateful for that.

Gaster hadn't been the nicest in his treatment of them but even though he had been young at the time himself, Sans sort of got the vibe that Gaster didn't have a firm grasp of right and wrong when there was a greater, more important cause for what he had been doing.  
The white points of light in his sockets took in the familiar surroundings as the skeleton allowed himself to reflect, roaming the familiar lab. He had nearly hit the thirty minute mark by the time he had reached the deepest level and Sans turned to leave before freezing, his pink slipper scuffing the cracked tile as he halted abruptly. His skull slowly turned back to the end of the hallway, eye sockets growing wide at the impossibly sight there.

There was a door at the very end of the hall. A door that had never been there before. Sans was certain of it and from the decimated security and overall look of the door itself, whatever was behind it was considered important enough to guard. He blinked into existence right before it, phalanges touching the surface to confirm that it was truly there.

"...this is impossible..." He murmured, deep voice echoing in the dead silence of the lab as his gaze darted about to take in everything about this anomaly. Because that was exactly what it was. This had never been here, in any timeline before.

An unfamiliar feeling resonated within him. Sans sucked in a few panicked breaths before he was able to recognize what emotion had gripped him so strongly. He had nearly forgotten what it had felt like...to hope.

Something was different in this timeline. Even if it turned out to be a bad time, it still was something new. Using his bony index finger, Sans aimed a precise amount of destructive magic at the door's heavy hinges, the metal shrieking as his magic tore the door from the wall. The short skeleton lowered the door onto the tile, out of the way and he peered into the bared entrance. Instead of the expected darkness and smell of decay, Sans realized with shock that there was still emergency power being supplied to this mysterious part of the lab.

Pushing away his unease, Sans walked through the long hallway that had the yellow emergency floodlights casting eerie shadows on his form. When he came clear of the hallway, the sheer size of the room had him pausing. One half of the room was covered in blueprints and notes all written in Gaster's native Wing Ding or Hands language. There seemed to be medical equipment and some unidentifiable machines as well. The other side...

Had a small bed, a dresser with some clothing and toys. Sans felt his bones shiver in response and his grin turned into a worried grimace. Someone lived here?

...were they still here? Sans scanned the room and saw a small staircase leading down and he paused. As much as he wanted to take his time and read the notes Gaster had left behind, Papyrus was expecting him. Now that he knew the location of this place, the skeleton could slip between space and time to teleport directly here.

Still, leaving here without the notes and exploring the entire wing left Sans feeling unsettled. He quickly walked over to the side with all of the files and gathered them up hastily. The files were thick and he rolled it up with deft movements and shoved all of them into his deep jacket pockets.

Turning his bright glowing pupils back on the staircase, Sans took them slowly; the hum of power here louder but the lights dimmer. His feet hit the floor and the skeleton froze at the sight that greeted him.  
Inside the dark lab was a glass cage that was halfway full of liquid, with many wires and tubes going through the glass to converge on someone trapped within. Even though it was dark, Sans could not pull his gaze away from the thing hovering in front of the limp figure.

It was a dim, flickering shape of a heart, cracked in multiple places, the same shade as Sans' magic when it was able to glow. Panic and concern gripped the Skeleton and he was pressed up against the glass before he had even willed himself to teleport.

This was a human! The sight of the damaged soul tore Sans to pieces in ways he had never felt before.

"can you hear me? hey!" Sans urged in a gentle but frantic deep tone. He froze when the human's eyes opened the barest amount.

There was a soft glow of teal in the human's left eye that had nothing to do with the color of their irises. His phalanges trailed up to touch his own left eye socket before he realized that the human was shaking.

"hey," his rumbling tone was excessively gentle now, "i won't hurt you. you don't need to be scared."

It had been so long that you had heard another voice. Even longer since you had heard anything remotely kind.


	2. Chapter 2

**Summary for the Chapter:**

> Ah~ I needed to write a bit more today. ^^ Even if people hate this, I think I will continue a few more chapters to gauge interest.

Your blurry gaze lifted to make out who was speaking to you as you fought to keep the instinctual fear that choked your breath down. This didn't sound like Gaster and it had been silent for so long. Squinting to clear the image, you tilted your head a bit more to take in the monster outside of your prison.

He, you were pretty sure it was male by the voice, was a short skeleton wearing a heavy jacket with a fluffy collar. After careful study of the expression, you saw that there was sweat beading on the monster's skull, his mouth pulled down in a frown. He seemed to be radiating concern and wasn't acting aggressive. 

Your shaking subsided a little as your gaze moved down his body, openly taking in his features. He shifted underneath the attention but remained quiet as if he sensed the situation called for it. He had drawstring shorts on and on his feet, pink fluffy slippers...

You swallowed and your attention trailed back up to his face.

"...You...aren't Dr. Gaster...." Your voice is raspy from disuse, barely audible. The skeleton stared at you for a moment longer before answering in that same soothing baritone echo.

"no. i am sans the skeleton." He answered, white lights in his sockets flickering between your face and your exposed soul, "i 'donut' mean to be rude in asking, but do you have a name?"

A vague memory stirs at the pun. It had been so long that most of your memories had deteriorated but didn't the Doctor mention that name and also puns in the same sentence? It was useless to try to call anything up, so you just swallowed again to wet your parched mouth.

"It's _______ ." You whispered, trembling as he begins to look around the glass cage you are in, "are you here to take me to Dr. Gaster?"

The skeleton freezes and his widened eye sockets take you in. Your attire was a thin hospital gown that ended mid thigh and your skin was extremely sickly, hair limp.

"how long have you been here?" The infliction in his voice is disbelieving, "gaster has been gone for...for a very long time."

You frown at Sans, "I have always been here. What do you mean by 'gone'?"

A brief look of confusion touches the lights in his eyes but then he was glancing over the cage again.

"we need to get you out of this. can you tell me how to free you?" Sans asked urgently and then his gaze fell on your exposed soul, "can you call your soul back in?"

The question makes hot tears burn your eyes, "I...can't." You choke out and his gaze is severely worried once more.

"why not, _____?"

You close your eyes and shake your head at the question. There is a heavy beat of silence before the skeleton sighs.

"look, my younger brother is expecting me. i don't want to worry him but i also can't leave you here. Would you...mind if i protect it?"

You stare at him, exhausted. At this point, you would probably be relieved if he took hold of what was left of it and crushed it to dust. You shake your head in reply, and lift one arm to point at a lever that was the 'release'. Sans hurries to it and pulls it down. The hiss of pressure releases and the few tubes that were actually connected to you blew out. You moan in pain and Sans makes quick work of the glass panel keeping him outside.

Even though he had been friendly so far; your trembling comes back in force; the teal glow in your left eye sparking nervously. Sans approaches you like a wounded animal and kneels in front of you. When you see one of his boned hands reaching forward, your squeeze your eyes shut, hot tears spilling down your face as you brace yourself to be hurt or killed.

Hard and warm phalanges are brushing the quickly falling tears away and you force your eyes open to look at the skeleton.

"i won't hurt you. i swear." The quiet noise of distress he makes causes you to choke on a sob, "humans don't usually have magic."

The statement is casual and you feel exhaustion biting at the edges of your consciousness.

"I'm not fully human anymore." You gasp and Sans' brow bones furrow in confusion but he doesn't press anymore. He withdraws his hand and unzips his parka, your nervous eyes following his movements as he lifts his shirt to bares the bright teal soul hidden within his left rib cage. It is bright, strong and you tremble with some unknown emotion as you stare at it. The whites in his eye sockets drop to your broken, dim soul and he reaches for it.

You flinch and brace yourself but end up sobbing in relief when his bony hands cradle your soul like it is precious, cupping it in a protective gesture. Sans looks at you before moving the soul closer to himself, expecting resistance. A human soul was determined and stubborn to part with its host but he is shocked when there is absolutely nothing that fights him. Being extremely careful, the skeleton places your soul in his right rib cage.

You are so tired. So confused. But his soul being so close to yours fills you with an indescribable warmth. Sans rearranges his shirt and zips the parka back up as your eyes fall shut.

The last thing you hear is his deep voice reassuring you and being lifted effortlessly.


	3. Chapter 3

**Summary for the Chapter:**

> Wing Dings don't like AO3 I found. X'D Oh well.

Sans teleports directly back to their house in Snowdin and lays your body on the red couch, trying to force his mouth back into its customary grin. It was difficult, as he was worried about the state of you but he managed as he pulled out his cell phone to call his younger brother.

"BROTHER! YOU ARE ONCE AGAIN LATE! WHAT IS KEEPING YOU?!" Papyrus' voice boomed over the phone and the skeleton checks to see if it had disturbed you at all. You hadn't moved but were shivering.

"something came up, bro. look, i have someone at our house that needs some help but i can't do this alone. could you possibly get Undyne and Alphys here asap."

There was a pregnant pause as the taller skeleton noted that his older brother did not crack a single pun in three total sentences.

"OF COURSE! I, THE GREAT PAPYRUS, ALWAYS HELP THOSE IN NEED!" The joyful skeleton declared and Sans neutral grin turned upwards slightly in a true smile. No matter the time line, he could always be sure of his love for his younger brother. Sans wanted to keep that innocence intact if this ever ended.

"thanks, pap. I appreciate your 'bone'ifide enthusiasm."

"ARRHHHHGHHH! SAAAANS!!" Papyrus complained an octave higher. Sans smiled fondly but then sobered a little as he noticed you seemed too cold. He unzipped his parka and shrugged it off.

"i am counting on you, bro." He murmured and hung up after Papyrus promised to fetch their friends as quickly as possible. Carefully plucking all of the folders out of his pockets, the short skeleton covered your body with the heavy jacket. He watched you a few tense seconds before your trembling died down. Relieved, Sans sat down on the floor and leaned up against the couch near your feet. Quietly he began to shift through many papers to try to get them in some semblance of order.

He remembered a bit on how Gaster organized his research and his reading in Wing Dings was rusty but Sans believed he would at least get some sense of what was going on with you. One of his bony hands rested absently over his right rib cage, over your soul as he leaned forward to begin reading.

(It has been a week since the human fell Underground with their infant.)

(I began my ambitious project on genetic splicing when the human's soul had been given to Asgore. He didn't have the will to kill a baby, so the infant was given to me for research.)

(If I can successfully get the child to take on Monster genes, the barrier may recognize it as both a human and monster soul to let them through.)

Sans frowned. It sounded like a good cause, one that W.D. Gaster would throw himself behind with abandon. He continued reading after adjusting to the jarring writing.

-The Infant's soul is incredibly resilient, perfect for experimentation. As of this writing, it was a pure, untouched white. If my understanding is correct, extremely young souls in both monsters and humans always begin as white. The human is female and cannot be more than one year in age.

20XX XX XX

After nearly have a year, I have completed my project. The human's genes have mutated so that they carry their own signature and have adopted the genetic code of Toriel, our Queen. I am uncertain if them both being female and intellegent played into the acceptance, but I have finished this phase.

Now that this is done, I am reluctant to let the child pass through the barrier. They are still too young and there is much to be learned here.-

Sans paused in his reading to check on you. Your breathing was deep and long, signaling you would sleep for a bit longer. He returned his attention to the folder and turned the page.

"...what?" He whispered, one bony finger tapping a series of Wing Dings.

Why was his name here?! The white lights in his eye sockets shot up to the top of the page.

-Since I will have to wait a good while before the human grows and can be trusted, I wanted to test on their soul, itself. I have dislodged it from the child's body without harming it. The trick will be finding out how to keep it outside their body to run tests.

20XX XX XX

I exposed the human soul to multiple test subjects today to see if I could draw any reaction in it. None of the test subjects were aware that the soul was present or aware that the experiment exists. After multiple tries, the soul of the subject reacted to my most successful subject, Sans on the day his magic manifested. They share the same color now, a bright blue. I now have many ideas in store.-

Sans began turning pages quickly, feeling panic and concern gripping him.

-..Magic manifesting today shows a duplicate of Sans' abilities...-

-...human began to complain of a pain but could not locate it...-

-...they tried to escape today...-

-...Soul is showing signs of damage even though it has stabilized and is kept from harm...-

-...barely shining and bares many cracks and chips...-

With a ragged, needless breath, the skeleton stopped on the last page; horror turning his face into a grimace.

-20XX XX XX

I have been a fool to not recognize it. Mating is common in monsters and preference of the soul plays a strong part. Her separation from Sans has damaged her soul to the point where I have to put her in containment. I am going to keep her as an anchor for Sans' soul to survive the time travel project coming up. Though this human is now sharing genes with the Queen, her soul simply would not survive the barrier. I am unsure of how many timelines her soul will survive to make sure that Sans will not blink out of existence, but humans are known for their determination. I am confident that their soul bond will keep them both within this part in time and space.-

This...this was impossible. Sans turned around carefully to peer into your face, his skeletal hand resting over your concealed soul hidden underneath his dark shirt. You were sleeping soundly with your nose pressed into the fur of the collar in his parka.

...That fractured, dim teal heart underneath his hand had been the only thing keeping him from following in Gaster's steps? To not existing at all? He didn't even want to think of the possibility that you were bonded to him at this moment. Sans' phalanges gripped the fabric as if in pain.

This had been the only timeline in which you had appeared. What if Frisk wanted to kill everyone again? Reset again? Had you only met because this was your last chance?

It was too much for Sans to take in so quickly and when the front door clicked open, the short skeleton grabbed all of the loose files and reported them to his room to hide them.

He immediately felt he had made a mistake when he heard his younger brother gasp in shock downstairs.

"SANS??! IS THIS A HUMAN?!?!"


	4. Chapter 4

**Summary for the Chapter:**

> I apologize that Sans is slightly OOC right now. As soon as things calm down, he will be back to his punny self. <3

You jerk upright and cover your ears at an obnoxiously loud voice, wide eyes taking in a very tall skeleton wearing a long red scarf that was standing in the door. You tremble at the freezing air being let in.

"NO WAY! LET ME SEE!" An equally tall and tough looking fish woman shoves the other out of the way and her face twisted into an angry expression. You breathe in a startled gasp as a spear materializes in her hand and she lunges for you.

Your arms fly up to shield yourself, panic gripping your heart.

WHAM!

"WHA?? GET OFFA ME, BONEHEAD!!" The monster raged and you hesitantly peek through your upraised arms. Sans was sitting on top of the struggling fish woman, who flailed under his sudden weight. The tall skeleton was gaping in surprise before he raised a finger.

"BROTHER! YOU SEEM TO HAVE TAKEN THE WRONG SHORTCUT! YOU ARE SITTING ON UNDYNE!" The loud skeleton, Sans' brother yelped.

"i chair a lot about what happens to my friend, pap." You notice that the two pinpoints of light that are usually in the other's sockets are absent and that Sans voice is pitched lower than normal.

"WHA?? THAT IS A HUMAN, SANS! LET ME AT HER!" Undyne screeched, trying to buck the skeleton off her back. Sans suddenly grips the back of Undyne's neck in one of his skeletal hands and squeezes in warning, the air crackling with suppressed magic. The sheer power and familiarity behind it is intoxicating; your left eye glowing teal in response.

"w-wait, Undyne...l-look," a timid looking dinosaur in a lab coat murmured from behind Papyrus. Undyne's gaze jerked back towards your face and her body slackened as she took in the glow around your eye.

"What gives? I am sure this is a human, I have seen them before!" She let out a frustrated scream when Sans did not let up, "alright, you fucking dweeb. I won't hurt her right now. Leggo!"

The air cleared of aggressive magic and Sans got off of the aquatic woman none too gently. The short skeleton was at your side before you had time to react to the change in atmosphere.

"you alright, ______?" His voice was back to it's soothing baritone and you paused before nodding. His attention moved to his tall brother.

"hey, pap. can you fix some of your famous spaghetti? I am sure _____ is very hungry." Papyrus brightened.

"OF COURSE, SANS! I, THE GREAT PAPYRUS WILL MAKE SURE YOUR NEW FRIEND DOES NOT GO HUNGRY!" The tall skeleton strutted into the kitchen and you watched as Sans fixed a much more serious expression on Undyne and Alphys. You are already exhausted again but the mention of food has you fighting to stay awake. The short skeleton glances at you before beginning to speak.

"alphys, ______ is a lost experiment of Gaster."

The yellow dinosaur gasped and peered at you with squinted eyes behind her spectacles. She had the look of another scientist but didn't seem hostile like Undyne.

"i read the files left behind." Sans murmured, white lights in his sockets staring into your face, "i would prefer to explain this once and not let papy know too much."

Undyne crossed her arms over her chest and you held your breath. You never had known the details of what you had been through, so you stared back at the short skeleton in askance.

"G-go ahead, Sans. We won't i-interrupt."

Sans recounted the contents of the file, omitting the part of him being bound to you by your souls. He needed time to take it in and if anyone was to find out first, it would be you. Undyne and Alphys remained quiet the entire time, gazes darting to you once the skeleton stopped speaking.

It wasn't a surprise that you were half monster, though your appearance was fully human. At least you knew the purpose of all the cold treatment as you had grown up. You felt something was off, but you nodded wearily in acknowledgement to what Sans had said.

"w-what did you need m-me for?" The reptilian scientist questioned at last. 

"you were able to study some of the human's biology from the last human to fall down. i just want to know if _____ is in any immediate danger." Sans glanced at you, "would you mind alphys looking you over? she is a nice monster."

You pause and then nod after a moment. It may be because he is holding your soul, but you want to trust what Sans was telling you. The dinosaur shuffled up to you and offered an arm, which you used to steady yourself and pull yourself onto unsteady feet. It was probably only by virtue of your magic that your muscles hadn't deteriorated completely.

The skeleton was watching your footing intently as Alphys led you into the bathroom.


	5. Chapter 5

**Summary for the Chapter:**

> Sans comes to a decision, no matter how it may turn out in the end.

Your body was tense as the door closed and you sat down on the closed toilet lid with a sigh. This was so taxing after what seemed like forever of not moving. The dinosaur seemed nervous but also held that same interested light in her eyes that you have begun to expect of scientists in general.

"I-I hope I am n-not too rude, b-but can you take that o-off, please??" Alphys adjusted her glasses nervously. You nod tiredly and grabbed the tattered hem of your white gown and pulled it over your head. She squeaks in surprise at your quick acceptance but then pauses to take in the three large gashes that are in between your breasts. Her gaze behind her glasses becomes sharper and she tenses, nearly rigid.

"Y-Your soul...? I don't..." She stammers and you breathe out a tired sigh.

"Sans has what is left of it." You answer and Alphys is utterly still at the statement.

"Y--you gave Sans your soul?? He has it, l-like, right now?" She asked, disbelief in her tone. You nod again, not seeing the issue but you flinch when she grips one of your hands gently, but firmly.

"Why would you do that?" Her tone was stern and the dinosaur was staring into your eyes with worry. Your confusion causes her to elaborate, "if Undyne had so much as tapped you with her spear, you would've...became dust!"

Your gaze lowers and you bite your lip, "its no good now. It is barely glowing and has all of these horrible cracks," to your horror, your vision became blurry with tears, "it's ugly. And useless compared to his."

Alphys is frowning at you, "y-you saw Sans soul?"

"Yes. It was beautiful, strong and bright. It made me feel warm."

There is a faint blush on Alphys face as she clears her throat, motioning to the deep scars on your chest, "and w-w-where did you get those?"

"Those are surgical scars from where Gaster found a way to un-tether me from my soul." The nervous monster stares at you with wide eyes. Alphys had always sorta idolized W.D. Gaster because of his amazing work but after seeing this...

"You aren't w-worried at all that he will...you know..." She made a vaguely violent gesture.

You pause.

"I don't mind if he does. I am tired and I haven't felt anything but fear in a very long time." Though...your soul being so close to Sans did give you a pleasant warmth.

Alphys is staring at you with horror, "_____, d-do you want to die?"

"I don't wish for death but I wish....I wish I had at least been u-useful," hot tears ran down your cheeks and your breath hitched, "now I am not human or monster. I don't h-have a place anywhere."

The sadness drains what little energy you had left and the world blurred as you collapsed. Alphys darts forward to catch you with a frantic shriek of the aquatic woman's name. The dinosaur cradles your nude body close to her as the door is wrenched open, a ferocious and protective expression on Undyne's face before her one golden eye widens in shock.

"What's wrong with her?" She demands and Alphys glimses Sans hovering worriedly by the door, a faint blue tinge along his cheek bones when he realizes you didn't have a scrap of clothing on.

"U-Undyne, can you carry ______ to Papyrus' r-room and get her c-clothes? M-Make her comfortable." Undyne blinks at the uncharacteristic solemn tone in her crush's voice.

"You got it, Alphys!" She agreed and the tall red haired monster gingerly took you from the scientist. Sans adverted his gaze and then looked back when Alphys called his name, motioning him over. He shut the bathroom door behind him and the whites of his eyes searched his old friend's face.

"what is the verdict?" His normally grinning face was slackened into a worried frown.

"Sans, do you really have her soul?" The short dinosaur demanded, her voice not stuttering at all because they had known each other for a while. Sans had once been in the scientific field alongside her. She didn't know the whole story but after Gaster had fallen into the core, Sans never returned to work.

"i do." He murmured deeply.

"Can I see it?"

The question draws a guttoral, deep growl from deep within his rib cage, "no."

"Why not?" She questioned with a frown at his tone.

"i h a v e t o p r o t e c t i t!" The change in tone rattles Alphys and she backs away a step. Sans struggles to get a grip over the possessive need that was rousing his aggression and he heaves a sigh before looking away.

"just tell me how bad it is....okay?" He finally breathes. The reptilian dinosaur steels herself before speaking.

"It isn't good, Sans. Physically, she is malnourished and weak. Food and healing magic would fix that. But the problem is with her soul. She told me that Gaster completely tore the tether she had on her soul. Her mental state is horrible. She feels she is neither a monster or a human. That she failed in her purpose for living. She gave you her soul and told me she didn't mind if you destroyed it."

"s-she said that?" Horror flooded his senses, his hand gripping the right side of his shirt. The timid scientist flinched at the sudden motion.

"Sans...would you?"

"N O!" Was the guttural answer and the lights in Sans sockets blinked out as the short skeleton lowered his head, "Alphys...can we save her?"

"I'm not sure, Sans," the monster fiddled with her lab coat, "damage on the soul is a serious and sometimes permanent thing. She has no determination to offer her strength from her human side."

There was a pause before Sans turned and opened the door to leave.

"Sans?"

He paused and looked back at his friend, "thank you, Alphys. i am sorry to have wasted your time."

"You are giving up?"

"i never give up." No matter how much he wanted to, "can you two stay at the inn tonight?" Frisk would be arriving to Snowdin tomorrow, having them closer meant that there were more chances that this timeline would continue to be much different.

But he needed tonight to think and to be close to you. Sans had never anticipated that his soul matched another's. Even if Gaster had forced it somehow, which the notes didn't allude to; you belonged to him.

"O-Of course. Undyne!" Alphys called for the towering fish woman and she emerged from Papyrus' room, carrying your limp body that was now covered by a clean, oversize shirt.

"We need to stay close if anything c-changes, o-okay? Is s-staying a-t the inn good for you?" The scientist began stuttering again at the mere sight of her hopeless crush and the woman beamed, showing off rows of sharp teeth.

"Sure, Alphys. We can watch some anime, yeah?" Undyne blinked when Sans halted in front of her and reached out his arms to cradle you. Getting the picture, the head of the Royal Guard carefully passed your exhausted body to the shorter skeleton.

"IS YOUR FRIEND SICK, SANS?" Papyrus asked, standing at the foot of the stairs. He offered his younger brother a strained smile.

"yeah, bro. she is in no shape to try your pasta tonight."

"THAT IS A SHAME. I PUT EXTRA GLITTER IN IT JUST FOR THIS OCCASION!" The taller skeleton looked put out that and Undyne stomped down the stairs and smacked his back.

"You should come with us to the inn, Pap! It'll be like a sleep over!" Undyne shot Sans a pointed look and he nodded, "sans will just be here on nurse duty, boring stuff."

"WOWIE! THAT SOUNDS FUN! IS THIS OKAY, BROTHER?" 

"of course, bro." He murmured and he watched quietly as his energetic brother bounded around and they were all leaving. His whites moved to your face and he teleported to his room, laying you down in the multiple blankets and fixing them around you.  
Hesitating, Sans also curled up around you, noting that he was finally taller than someone, if just by an inch or so. His sockets closed as he focused his magic around your shattered soul to support it. From what Alphys had said, your condition was severe. Sans sockets shot open when one of your hands fisted in his shirt and you cuddled into his rib cage.

A minute of shocked silence passed and then his expression gentled.

"i didn't expect you." He murmured in a hushed tone, his left socket glowing steadily as the skeleton stared down at your slumbering expression. You weren't resting easy.

"but now that i know you are mine..." Sans carded your hair softly between his bony fingers gently, "i don't want to let you go."


	6. Chapter 6

**Summary for the Chapter:**

> Plot, plot and more plot! And serious Sans. 3

Your eyes open slowly and you realize that you aren't in the lab. In fact, you are pretty comfortable, surrounded by soft blankets and warmth. A gentle touch is cradling your head and you look to see that you are cuddled into Sans side with your head laying over his hidden soul. The skeleton is staring at you, whites moving over your face worriedly. His right rib cage is glowing teal under his shirt.

"i was afraid you weren't going to wake up...." His deep tone washed over you and you marvel at how you hadn't flinched away from him. You felt calm and safe like this, so you don't move.

"What time is it?" You flinch at your rough voice and Sans shifts under you, reaching to get a glass of water from his nightstand and offering it to you. Smiling softly, you thank him and finally sit up to take small sips.

"it's either very early or late, depending on how you think about it." He said in an amused tone but his mouth was tight in a worried grimace.

"Sans? What's wrong?" You ask quietly. The whites in his sockets flicker over your face before darting away to stare off at nothing.

"nothing." He mutters in a quiet baritone. You frown and stare at him silently until the silence and pressure apparently get to him; small beads of sweat beading on his skull.

"guess i can't afford not to tell you..." Sans said quietly before his gaze was locked with yours, "i think this is our last chance, after all."

Last chance?

"you asked me where Gaster was, _____. his files show that you were contained before he started the project i was involved in. he had this ambitious theory that if he could just figure it out, that we could jump back in time so we were never trapped in the first place. our king doesn't like to kill humans and Gaster was close to Asgore."

"He wanted to travel through time?" Your voice is shocked and Sans nodded in response.

"i can't remember what happened on that day, but only a select few monsters even remember that W.D. Gaster ever existed. he had been utilizing the Core when something must have went wrong. what Alphys' best guess was that he had fallen into the Core and his existence scattered throughout time and space."

Sans is quiet as you let it sink in that the monster who had raised you had met with a horrible fate. But then...

"You said you were involved with the project?"

The lights in his eye sockets dimmed and the digits of his fingers tangled together in a bracing gesture.

"i was the test subject." He breathed and your eyes widened in response. When Sans had mentioned Gaster, you thought he had been a colleague of equal standing. The skeleton claimed he couldn't remember that day...

"Was it...did the Doctor's experiment succeed?" Your voice is quiet, not from disuse but out of respect for the tension coming off of the other monster.

The silence seemed to stretch forever.

"...it did. but not in the way he had hoped for." Sans murmured finally, twisting his bony fingers together in distress. Had he ever told anyone else this? You kept quiet, worried that if you broke the silence that Sans would stop talking.

"i...didn't notice anything different for quite awhile. years in fact. pap grew up and we lived peacefully here. i thought it had failed because i didn't go back in time." A bitter chuckle rattled his shoulders, "it only worked when Frisk fell the first time, murdered everyone and then i woke up to relive those three days over again, with my memories of the first timeline intact."

"Who is Frisk?" You asked, completely confused.

"they are the human child that fell to the Underground yesterday." Sans said and sighed at your puzzled expression, "i suck at explaining this."

Sans radiated frustration and despair and you found your hand reaching out to tangle with his bony fingers. The skeleton blinked their sockets as his whites took in your joined hands and he looked at you in awe.

"Can you try?" You questioned, "I want to understand. You said that this was our last chance..."

"i...i...have been reliving these past three days. over and over... sometimes Frisk only kills a few monsters. sometimes my last memories are of everyone alive and passing through the barrier. in really bad times, Frisk kills everyone. i never know which version of Frisk will appear but i know they are at fault for the repeating timelines."

You swallowed nervously. A kid was responsible for all of this? You didn't know a thing about humans, even though you had originally been purely that. It sounded a little far fetched but you existed from Gaster's influence. And for some reason, you just sensed that Sans wasn't lying about this.

His emotions were too raw, his pain too real for this to be a lie.

"Why do you think this is going to be the last timeline?"

Sans eye sockets widened, his fingers gripping yours slightly harder.

"you believe me?"

"Yes." You answered simply.

"why?" The question was so puzzled and strained that your breath catches.

"I can just tell." You smiled cautiously in response and Sans stares at you for a long moment before accepting your answer without any fuss.

"because you are here. in every single timeline, that part of the lab didn't exist and i never found you. Gaster had said you served as my anchor, so i don't blink from existence just as he did. it has to mean something, that we are both here." His voice is pitched lower and you don't fight him as he cups his free skeletal around your already joined hands.

"What do you mean?" It comes out as barely a whisper. His skull cocks to the side, his hand that was supporting your initial hand-hold reaching down to the hem of his dark shirt, lifting it to expose his rib cage. Your feeble, fractured soul is surrounded by his strong magic and your gaze trails between them, inwardly feeling ashamed at him having to hold that so near his own beautiful soul.

"did Gaster never tell you..?" Your puzzled expression had him continuing, "no two monster or human souls are exactly the same. especially in color. they only take the same shade as another soul they are intended to be with."

It takes a moment for what he had said to sink in fully, but when it does; you are unsure of how to react. Soul mates existed? If so...fate had a very sick sense of humor if you fully understood what Sans was telling you.

"What...what am I supposed to do?" Sans did feel right, trustworthy, warm and kind. Were you supposed to automatically have feeling for him right at the start? Or was your soul too broken to ever be worthy of his shine.

The skeleton lets the fabric fall back into place and he dislodges his hand from your grasp before pulling you into an embrace. Instead of being rough, hard and uncomfortable, you feel warmth within Sans strong frame.

"i don't expect you to do anything, ______. but could you maybe stay with me?" Sans questioned in a quiet tone. You nodded immediately but the short skeleton was already shaking his head.

"promise that you will be with me...u n t i l t h e e n d...?" The ragged question pulsed with his intoxicating magic. The full gravity of the situation was just dawning on you. Sans had lived through countless timelines, that only lasted three days. The thought of him fading from existence shook you to your core. Papyrus would possibly never remember Sans had ever been there.

And you doubted you would survive a 'reset' with the condition your soul was in. Your arms came up to cling to the fabric covering Sans' spine.

"Until the end." You said in a gentle but firm voice.


	7. Chapter 7

**Summary for the Chapter:**

> I hope everyone enjoys this update! ^_^ I have already decided on a really amazing outcome. One that may break a few hearts but please hang in there.

It felt like you hadn't slept much at all after comforting Sans and learning his secret, when you jerk awake again. The light coming through the window makes you wince and for a moment; you think that is the source behind your rude awakening. The lack of warmth by your side signals that the short skeleton woke up before you, so surely it wasn't just...

"Ah~" You wince at a needle like pain and then burn in your side and sit up so you can raise the over sized tee up to inspect the area.

You freeze and stare at the exposed skin. Two, angry red and prominent 'x's were burned into the soft flesh. They were really small; no bigger than your pinky nail, but radiated a burn that was uncomfortable. As you look at them, your teeth clench together as another 'x' appears. Hissing, you lower the shirt in confusion and wonder if you should seek out Sans for help.

But...would it be fair to complain about this in light of everything that was happening? Worrying your bottom lip, you falter before deciding to leave Sans room. All the way down the stairs and into the kitchen, your side stings.

"HUMAN!" Papyrus greets you from plating up some rather...sparky looking spaghetti, "YOU ARE JUST IN TIME FOR BREAKFAST! I, THE GREAT PAPYRUS, WARMED UP MY FAMOUS SPAGHETTI DISH YOU MISSED OUT ON LAST NIGHT!"

Despite his booming voice and pain, you smile at his enthusiasm and sit down at the table, "thank you, Papyrus. Do you know where Sans went?" The tall skeleton places the plate in front of you with a fork and sits beside you with his own dish.

"SANS IS USUALLY SUCH A LAZY BONES AND SLEEPS IN LATE, BUT HE IS OUT AT THE SHOP TO FIND YOU SUITABLE ATTIRE!"

Oh...That was really nice. You smile softly but wince as another spike of pain hits you. Thankfully Papyrus didn't notice as he had dug into his spaghetti. You didn't want to worry anyone. You pick up your fork and twirl some of the sparkly noodles around it, biting into the noodles. The...glitter? definitely doesn't belong and the sauce tastes a little odd, but Sans' younger brother is staring at you hopefully.

You swallow and smile warmly at him, "it's great. Thank you." You praise and the skeleton straightens, an orange flush appearing on his cheek bones and sparkles shining in his sockets. You feel much better about eating the crunchy noodles if it brought that type of happiness.

"WOWIE! THANK YOU, HUMAN!!" You don't correct him, you look human enough, "OF COURSE IT IS GREAT! FOR I AM GREAT AS WELL!"

You manage to eat all of the noodles under Papyrus' happy watch just in time for Sans to appear in the kitchen holding a pair of boots and warm clothes. The whites in his sockets flash from you, to the plate, to Papyrus before a warm smile blossoms.

"you enjoy pap's cooking?" He asks softly, though there is an undertone in his voice that hints that he appreciates the gesture very much.

"Yes, it was special," you answer and Papyrus is all starry socketed again. Sans holds the clothing and boots out to you to take as you stand. The stinging in your side makes it harder for you to keep a happy expression at the comfortable fabric.

"i hope these will fit you. we don't have many things in the shop here."

"Thank you, S-Sans." You stutter as a particularly harsh sting bites your side. When his expression falls slightly, you hurry on, "I will go try these on!"

You manage to smile at him and walk (despite your urge to run) to the bathroom. Shutting the door behind you, you frantically tug off the shirt that belongs to Papyrus. Eyes widening, you take in the tiny 'x's burned into your left side. They began just below the breast and extended to your hip. You watch with nervous eyes as one more 'x' burns into existence.

Was this some type of strange, monster rash? It was painful, but not unbearable. You waited a full five minutes, turning on the water so you weren't just standing idle to see if anymore were going to show up. But it seemed to have stopped.  
....maybe this was just a rash after all? 

Deciding not to bring it up because it seemed minor, you tried on the deep green sweater and grey slacks. The top reached mid-thigh and you had to tighten the drawstring all of the way on the slacks. They were a bit long, but you tucked them into the boots that ended up fitting nicely to take care of your height issue.

You exit the bathroom to find both of the skeleton brothers sitting on the couch watching a robot on television. Sans relaxes at the sight of you.

"those look good on you. sans'sational." He praised with a wink and Papyrus yells his displeasure while you smile, your face flushing as a small chuckle escapes your lips. 

"BROTHER, IF YOU DON'T START YOUR ROUNDS THIS INSTANT, I WILL BE VERY CROSS!" Papyrus springs from the sofa as he threatens the short skeleton. Sans smile drops a bit and his gaze locks on you.

It takes you a moment before you remember what was happening today, but when you do; you understand the tension there. 

"right behind you, bro." Sans promises and Papyrus straightens with a happy expression.

"THAT IS THE SPIRIT, SANS! WE SHALL CATCH A HUMAN AND I WILL FINALLY BE PART OF THE ROYAL GUARD!" He looks at you, "A HUMAN THAT ISN'T OUR NEW FRIEND, THAT IS!"

You smile at the 'our' and nod at Papyrus before he struts through the front door. Sans is immediately at your side and his tense expression causes you to instinctively reach out and hug the monster. You could feel his start of surprise but he returns the embrace strongly. The 'x's in your side burn from the friction under one of his arms, but you don't mind if it is him.

"do...do you want to come with me?" The question sounds so cautious that you tighten your embrace.

"Remember we promised?" You remind him gently and he pulls back with an elated and pleased expression. But he looks so worried that it squeezes your heart.

"what if it is a bad time?" He pressed, sweat beading on his skull. You pause at the thought. A 'bad time' was a human child killing monsters. Killing all of them. But Sans was sure that this would be the last timeline.

"Even if." You confirm with a smile and Sans' gaze turns grateful and warm.

"thank you, _______." He murmurs in his deep voice and you nod before suddenly you are surrounded by snow. A little disoriented, you stumble but Sans quickly catches you and steadies you.

"A..a warning would have been nice," you say in a shaky voice. You are surrounded by thick woods, snow drifting around you. Sans apology is barely there as you take in the beautiful sight of the snow. Puffs of cold appear as you breathe and you smile.

"first time seeing snow?" Sans asked with a wide grin and you nod. He holds out his skeletal hand you you take it, letting him guide you through the forest. The gentle crunch of the snow as you walk and the warmth radiating from your joined hands is so lovely.

....who would ever want to leave here?

"It's so beautiful." You say softly and Sans grins widely at you.

"not as much as you."

You let out a startled but pleased laugh.

"Did you just flirt with me, Sans?" You ask, beaming up at him. You were glad that Gaster took care of your social education so that you could recognize the ques of others.

"maybe...?" He draws out the word mischievously and winks, "will you hold it against me?"

"What would I hold against you?" You ask lightly, noticing a faint ringing in your ears. Maybe it was from the snow?

"your body." He states, pleased. You snort and dissolve into giggles.

"Oh," you gasp and then wince when the ringing grew louder. Sans stops and his whites track across your features, worried.

I know now who I was protecting...

"________?" The call of your name is nearly drowned by a soothing female voice in your head along with that painful ringing.

...when I was locking this door....

"....S-sa..." You taste metal in your mouth, your vision fading into static.

It was Them!

......

......

"---"

"h--"

"wa..ke...ple--!"

You issue a weak noise of askance and force your eyes open. The cold floor of the snow covered forest is seeping into your legs, the rest of you was still warm from Sans cradling you. His left eye is alight with teal flames, the pupil fixed on your face.

"D-did I fall?" You question weakly, your chest is burning.

"are you alright?" His deep voice is urgent and scared. You swallow and blink, trying to figure out what happened. You had heard a voice...and your chest hurt. But you were able to stand back up with the short skeleton's aid.

"I may have just fainted?" You are unsure and Sans doesn't seem to know what happened to you either.

"are you well enough to take a shortcut? we are almost late." He questioned, frustrated and concerned. You nod and he takes your hand and suddenly you are close to the tree line, still hidden but you could see a door set into the mountainside.

The door opens and Sans' hand squeezes yours tighter.

A small child with brown hair and a long striped sweater emerges from the Ruins.

The wind is picking up and blows dust from their shoulders, a knife clutched in one small hand.

The smile on their face twists into something ugly.


	8. Chapter 8

**Summary for the Chapter:**

> The Underground loses one of it's most precious lights.

You feel your heart skip a beat at the sight of the child. The violence radiating off of them causes the hairs on your neck to stand on end. This was a dangerous individual. But...for some reason, perhaps that you had recently fainted, you could swear that you could see their soul. ....Souls? Or was that a double image from possible injuries. Sans arms wrap around your form tightly and you are back in his room.

One look at his expression feels like your soul is finally being crushed. Sweat is beading down his skull, his left eye socket burning a bright teal around a vivid yellow pupil. In fact, it seemed to be sparking as blue tears pool over the rims of his sockets and streamed down his face.

"no.no.no." His deep voice is tight with suppressed aggression and panic.

"Sans..." You whisper and reached out to cup his wet cheek bones, the blue tears spilling over your fingers. His own skeletal hands shoot up to cover yours and that fiery pupil is trained on your face.

"i want to go out there to kill them." He growled, though his touch was gentle, "but if i do that; the timeline will end!"

You understand. You were also afraid.

There was only today and then tomorrow that you both had left. It may be extremely selfish of you, but you wanted every moment you could. You had only begun to see what happiness life could possibly offer you. The warmth of Sans embrace, his kindness, the beautiful soul he possessed. The cold and gentle snow. Papyrus' zeal for life.

You didn't want it to end so soon. Tears welled in your eyes.

But in asking for the rest of the timeline, everyone else would suffer. Even Sans.

"don't cry, ______." Sans murmured softly, even though his own warm tears were still soaking your hands resting on his face.

You didn't want to let this sweet skeleton go either, you realize. You had only just found out that you held a very special bond with him. You liked him. But you wanted the time to fall in love as well.

"Am I a bad person...for wanting two more days?" You gasp and his eye sockets widen before you are being held tightly against his chest. Nuzzling against his parka, the blue material is absorbing your tears. There was no reassurances to be offered here. Sans knew that Frisk was the driving force behind the timeline. This was out of his hands now; but damn him if he didn't fight harder at the very end.

"never. you are amazing and i am so glad i found you." He rumbled in his deep voice, "i wish i could stop this."

You pull back to look at his face, "everyone at the inn..."

His eye flashes with panic and pain.

"what...what do i do?" He didn't want to see all of his friends dying again, his precious little brother falling to Frisk.

You pause, "can you tell them? About the timelines and what is going to happen?"

His expression is pained.

"In the end, shouldn't they deserve to know the truth?" You know it is a horrible thing, but Sans nods with a grim frown after a moment.

"can we at least leave out that this is the last timeline, _____?" He pleaded and you smiled, eyes shimmering with fresh tears and you blinked, nodding as they fell.

Hope was one thing you wanted everyone to hold onto, even though yourself and Sans had come to grips that there was nothing to hope for. With a reluctant sigh, the short skeleton teleports you both to the inn. After asking the bunny at the desk; you followed Sans into the room where the trio was relaxing and watching anime on the television.

One of your shoulders is stinging horribly.

Their laughter cuts off and Sans freezes under their gazes.

"G-glad t-to s-ee you u-up and about, ______." Alphys stutters with a warm expression. Undyne is staring at you with concern but when you look directly at her; her expression turns petulant.

"Yeah, the nerd here told me to lay offa you. You are too soft for me to beat on anyways."

"BROTHER! WHAT IS THE MATTER?" Papyrus shouted, his attention one hundred percent trained on Sans. You take his hand and squeeze it reassuringly.

"there is a human on the way here now." Sans revealed and Undyne and Papyrus are on their feet and getting ready in a flash.

"WHERE?" Papyrus asked eagerly, "I WILL CAPTURE-"

"pap." The word is flat and pained. Undyne pauses in the middle of putting her armor back on at the tone. Papyrus now looks tense and confused.

"Brother?" His voice is soft and wavering. Sans glances down at you and you nod, still holding onto his hand. Alphys is glancing from your faces to your joined hands.

"the human is killing every monster they meet." Sans paused, "and i have something to tell you..."

They all listen attentively as Sans reveals what he told you last night, omitting the part where you two were going to disappear and that there would be no more second chances. They grilled the skeleton but they believed him, much to his shock.

"If all three of us take them on at the same time, I think we can win, Sans! Don't write us off just yet, dweeb!" Undyne swears with a toothy grin.

Papyrus had been wilted until then, but perked up, "YES, BROTHER! IF BOTH UNDYNE AND I DEFEAT THE HUMAN, NO ONE ELSE NEEDS TO BE HARMED!"

They hadn't really understood Sans then. He smiled shakily, "maybe..." 

"I-I will evacuate e-every-one, S-Sans!" Undyne swore, and she looked tense. Perhaps she had understood, since she was a scientist as well. He nodded in response.

"please." He murmured and the dinosaur hurried to get ready. Once everyone was dressed and armed, Papyrus hugged his older brother tightly, lifting him clear of the floor. You let go of the short skeleton's hand to allow him to return the embrace.

"BROTHER! YOU AND OUR FRIEND MUST FIND SOMEWHERE SAFE AS WELL! WE SHALL TAKE CARE OF THE HUMAN AND PROTECT YOU!"

"i-i-" Sans voice is choked as his grip tightened, "i love you so damn much, bro."

"Sans," the tall skeleton's voice is pitched low and gentle, "don't be sad. Nothing will happen to us."

Sans choked on a sob and Papyrus sat him back down and smiled at him before turning to you, "TAKE CARE OF MY BROTHER, _____! HE IS VERY, VERY GREAT! EVEN GREATER THAN ME, WHICH IS SAYING A LOT!"

You smile and force yourself to smile for Papyrus' sake. To his and Sans' surprise, you rush to the tender hearted skeleton and hug him around his slim hip bones. You don't even need to look up to see that he is flushing orange.

"H-HUMAN! FEAR NOT! YOU ARE MY FRIEND! AND THE GREAT PAPYRUS ALWAYS PROTECTS HIS FRIENDS!" Papyrus declared. Undyne smirked at you as you let go of the flustered skeleton.

"Yeah, nerd. Nothing to worry about." She says in a rough and confident voice. They are leaving the inn all too soon and you stare at their retreating forms before the falling snow makes it impossible to make them out.

"can you stay with me....even if i follow them?" Sans asks quietly, the dim whites in his sockets trained on your eyes.

You swallow. You don't want to see them die. But Sans had seen this so many times alone already, so you nod. You take his hand and begin walking. Your left shoulder was burning all the way down to undoubtedly meet the angry 'x's of your side.  
It wasn't important.

You needed to be here for Sans. Your walk is quiet and tense. There is really nothing to say. When you spot the vague shape of Undyne and Papyrus standing tall in the road to Snowdin, Sans teleports you both close, but out of sight.

You don't let go of his hand.

"HUMAN! I HAVE HEARD THAT YOU ARE COMMITTING MURDEROUS ACTS. YOUR REIGN OF TERROR ENDS HERE!" Papyrus booms at the much smaller form of Frisk, "IF YOU LAY DOWN YOUR WEAPON HERE AND NOW, WE WILL SHOW YOU MERCY!"

Undyne doesn't correct Papyrus and you marvel at his kindness. So, it seemed he was still ignorant that the humans that fell down were still killed after being captured. She silently grips a glowing spear as the child takes a step forward.

A fiercely glowing red soul appears in front of them and you blink, trying to clear the double image.

"LAY DOWN YOUR KNIFE, HUMAN!" Papyrus commands, though he looks nervous now that Frisk seems set on fighting.

"oh, papy..." Sans whispers and you glance at the skeleton to see vivid blue tears leaking from his sockets.

A clash has your eyes jerking back to the fight. Undyne is right in front of Papyrus, blocking a blow from Frisk's knife that had been intended for the hesitant skeleton. He straightens and raises his hands upon seeing Undyne attacked, bones jutting up from the snow as the human skillfully dodged.

Heavy bone, white and blue flies at the child, glowing blue spears flying from Undyne's grasp almost too fast for you to see.

But...Frisk was dodging them all.

They knew. You realized.

They couldn't hit Frisk because they knew how Papyrus and Undyne fought.

And even together...

SLASH!

Your vision darkens but you hold onto your consciousness desperately as Papyrus' shocked expression burns your chest.

"I...I did not expect...for us to not become friends..." Papyrus whimpered. Sans grip on your hand is so tight that it is hurting. You don't say anything, too caught up with the much more painful sear on your chest and the heartbreaking sight in front of you.

"You...you only could try a bit more..." His head tumbles from his shoulders, "I believe that...you could be good..."

A red scarf flutters in the wind as Papyrus dissolves into dust.

It feels like your heart explodes and Undyne's scream of rage is the last thing you hear before you faint once more.

Why couldn't you be stronger?


	9. Chapter 9

**Summary for the Chapter:**

> Oh gosh! I must clarify this! I AM A HUGE SOFTY! I may torture my readers with angst but I will always, always provide a happy ending!
> 
> So please stay DETERMINED!
> 
> Also, lullaby taken from here, Frisk's part. Not all of it fit yours and Sans situation, but two verses did. So credit goes to this wonderful video.
> 
> https://www.youtube.com/watch?v=3oQOiC4_AfU

When you open your eyes next, Sans had your head resting in his lap; his sockets empty of any light. 

"Sans...?" You whisper and the lights that are his pupils flickered into existence and scanned your face in relief. You are shocked when his arms wrap around one shoulder, the other cradling your head to pull you up into a hug.

"oh god...i thought you were gone." He choked.

He looked so unbearably sad. From the shards of memories you still had, what the Doctor had said about Sans was that he was happy most of the time and always cracking jokes. It shouldn't be like this....

"Undyne?" You were reluctant to ask; feeling Sans' frame shaking against yours.

"she is gone."

You close your eyes and silently hug him back. Your entire torso is on fire.

"i am breaking." Sans whispers fearfully and you pull back, alarmed.

"What...?"

He silently unzips his parka and lifts his dark shirt to reveal the two souls. Yours is a complete mess as always, but the chip in his beautiful soul has you reaching forward. The skeleton doesn't flinch, watching you with trusting, sad eyes as your fingertip gently touches the damage. You tremble and you gently cradle the precious soul in your hands. San's sockets widen when you bring the teal heart to your lips and press a kiss to the fracture.

"nngh!"

You pull back quickly, "I'm sorry!"

There is a bright blue blush along his cheekbones, "it...it didn't hurt me, _____. it's fine."

....oh! Your face burns with warmth, but you don't let go of his chipped soul.

"Did I overstep...?" You ask cautiously. His frown pulls upwards just the slightest.

"of course you didn't. it feels nice." Sans murmurs reassuringly. You smile softly and then realize that it is quite dark where you both are curled together. You could hear the faint rush of water and looking in the distance, there is a lake with deep blue glowing flowers.

"Where are we?" You question and Sans gaze moved out towards your surroundings.

"this is waterfall cave. the echo flowers are usually whispering whatever they had heard last, but they are quiet."

Your left leg burns horribly, "h-how much time do we have left?"

The white lights in his eyes dim a bit, "you were asleep for most of the day. we have roughly a day left, if not shorter." Your eyes lower to his chipped soul. Sans... He had lost all hope.

"are you alright? this is the third scare you have given me." His voice is pitched softer, as if to hide the pain he was going through, clearly represented in the soul you held. You chew your lip worriedly and Sans whites flicker down towards the gesture before looking back into your eyes.

"I...I don't know. Something weird has been happening..." You murmur. Holding out the heart with the single chip in it, Sans accepts it to return it where it belonged. He tenses in surprise when you grab the hem of your green sweater to lift it. Even though he was surprised for another reason, your eyes widen when you discovered the most of your skin was gashed with the 'x's. 

And...

In the scars where Gaster had operated on you were three heart shaped burns; but they had color to them. One was green. Another a deep blue. And the last...orange...

Your heart plummets.

"Oh my god..."

That mysterious female voice.

And Undyne...and Papyrus.

Sans' left eye socket burst with sudden magic and his skeletal hand rested over the orange heart, the other taking hold of your hip. You blush a little because the touch is incredibly intimate. Your breasts were covered, but it felt like you were naked anyway. Your eyes raise from the colored marks and you watch his magic pupil linger on the heart before taking in all of the 'x's.

"papy..." He whispers softly before looking at you in worry, "does it hurt?"

"Hmm," you nod in response, "it burns pretty bad at first, but then it is just uncomfortable. His teal gaze take in the visible marks.

"are...are they everywhere?" He asked hesitantly.

"Not yet, one side of my back and my hip...the legs right now though."

"i think this is Frisk's kill count," he looked confused and frustrated, "but i don't have a clue why they are showing up like this."

"All of these marks..." You feel a little ill at the thought and didn't even want to count them. There were so many.

"every time you have passed out is when a boss monster has fallen." He looks incredibly sad and withdraws his cool fingers from your burned flesh. You lower your sweater and hug the skeleton, nuzzling into his shoulder.

"Sans, please don't give up yet." You whisper near his skull and he shivers; holding you tighter.

"i wish i could. i want to," his hand trails down your spine, "but if i do; Frisk may hurt you. if i can defeat them enough times, they may just reset so you won't have to suffer."

Tears well up in your eyes, "I don't want you to suffer either!"

He hushes you, "i know. i can feel you through your soul. i know you aren't lying about that."

You blink and lean back to see his expression. The magic in his left socket had simmered down to just a teal pupil and there is a small blue flush on his face.

"i could have sworn that someone in one timeline said that monsters were strange...because they loved so easily." He murmured in his deep voice.

"Y-You love me?" But you had only been here for a short time. Sans tilts his head at you and the smile there makes your stomach do weird but pleasant things.

"of course i do, ______. You are mine."

If you didn't know beforehand that your body was covered in burns, you would swear that your entire body was blushing in response. He was so sure. His expression gentles at your embarrassment and confusion.

"don't worry yourself about it. if your soul was in better shape, i am sure it would be able to sense that i am yours as well." He offers you a tentative smile.

"How do I know when I love someone?" You ask helplessly.

"you'll know. i promise."

What if you didn't have enough time? You didn't want to bring Sans back down though. He was smiling softly at you, his pain briefly forgotten.

"S-Sans...could you tell me about your life? I want to know everything about you," you requested. He looks puzzled.

"i have already given you a jest of it. not much else to tell..." 

"No...I mean like, memories. Personal stuff." You blush. The grin that follows brings you so much relief.

"ah... you want to get 'personal' huh?" He chuckles and then his pupils return to their normal white pinpoints of light.

He begins to tell you about his years in Snowdin. About how Asgore came every year around Christmas to visit everyone and ask what they wanted. His voice is incredibly gentle and fond when he recalls how Papyrus used to only come to his hip and that he had been so frightened of 'Santa'. But then every year after that one, Papyrus greeted him with eagerness and enthusiasm.

About when Sans first tried Papyrus' first try on Spaghetti, which turns out to have been so much worse than what you ate that morning. But he said that he ate it entirely but made sure to be discreet after that when some of the batches were just too much to handle.

The skeleton monster told you about his desire to see the stars, the real stars one day and his voice trailed off but you quickly asked about how Papyrus and Undyne had known each other to distract him.

It probably had been three long hours of talking before Sans' words became staggered and he had trouble keeping his eye sockets open.

"pap used to have me tell him a story every night....to help him...have a good rest...." Sans murmured.

"What helps you sleep?" You ask gently.

"i really don't want to." But he ends up answering after a pause, "i sort of always wanted someone to sing me to sleep, like in the books in the library."

He looks up at you tiredly with a pleading look and you swallow nervously, "I am not sure if I am too good at it, but I can try. I will make something up for you..."

"just for me?"

Sans looks relieved and he holds out his arms. You snuggle into his chest, cautiously sitting in his lap but it is more strong and sturdy than you expected. When you thought of bones, it was usually thoughts of rough and brittleness. But Sans was incredibly strong, like warm steel.

He closed his eyes sockets as you laid your head against his chest, safely in his arms. You think for awhile quietly, on everything about him...how he made you feel...and lyrics came to you even though you weren't sure if he was still awake to hear them.

"It's not fair to be alone," your voice is soft and slow, "after what you've been through. So let me just ease your pain; please just let me stay with you."

His eyes are closed and he is breathing slowly.

Was he asleep?

"...I continue to reach out. I won't abandon you." Had his grip tightened or was that just your imagination? "Determination fuels me, to keep trying to save you...."

You keep repeating those two verses softly until you drift off.


	10. Chapter 10

**Summary for the Chapter:**

> I sinned just a little bit in this chapter. X'D Also, just as a heads-up; this story still has awhile to go. ;)

You wake up to the gentle motion of steady footsteps; your eyes opening slightly to look up at Sans. As your head shifts on his chest, his eyes gentle and he returns his attention back on where he is carrying you. Your head feels so heavy and your skin feels like it is on fire.

Where were you now?

It seems to be a hallway, a very luxurious looking one. You had never seen so many shades of gold, cream and yellow before. It was beautiful, but the continuing silence from the skeleton carrying you brings an unsettling feeling of unease.

"W-Where...?" You wince, your voice is like sand paper.

"try not to speak, ______." The tension in his voice raises alarms in your head, but it is hard to focus. You look at him in askance and he sighs.

"your soul...isn't doing too well. you have been asleep most of the day..."

His words slowly sink in and a whine surfaces when you realize that you had missed most of your last day with Sans. 

You pass the hallway and enter into a more bland area and Sans is taking a long flight of steps downstairs. You look around once he stops. It is a basement and to your left are seven caskets with hearts on them. They must be the souls that the monster king had collected so far...

Sans goes the opposite way across from the caskets and he sits down with you still cradled in his arms against the wall. The lights in his eye sockets are out and his usual grin is tilted downwards in a frown.

You reach up and frame his skull with your hands, drawing his attention. One of his warm skeletal hands rests on top of yours and he is quiet for a moment before speaking.

"if someone had told me in the last timeline that i would cease to exist, i would've been relieved," he murmurs, deep voice rumbling, "but i found you. i don't want this to be our last chance. not when Frisk is on a murderous rampage."

"W-what happens now...?" You whisper in a rough voice and the skeleton stares at you silently.

"i will fight them in the Hall of Judgement, like i always have." He answers.

An uneasy silence follows that statement. You don't want Sans to fight that human child. From your seared skin, you could feel how many monsters Frisk had murdered. That the person you were bonded to was going to face them alone.

It filled you with fear.

"what would you have wanted, ______?" Sans asks, the smooth bone of his thumb stroking the hand on his face, "if we had been able to survive?"

"I..." Your voice breaks and you swallow back your emotions, "I would've wanted to stay by your side. In S-Snowdin, or the surface...it didn't matter."

There is a faint glow in his left socket as you continue after catching your breath, "i wanted to experience all of the things I c-couldn't before with you."

"_____...." His voice is strained.

"But I am glad I met you, even if just for a little while," you whisper and he tightens his grip on you, clinging to your damaged body and you hold him back as tight as you can muster, your fingers fisting the blue material of his parka.

"i have already asked you to stay with me during this terrible mess... would it be too much to ask for one more thing?" Sans asked against your hair. You shake your head and he leans back, but only stops a few inches away from your face to stare at you with one blazing teal pupil.

"i never expected to be soul bound in my life and i don't know how a lot of thing would work because i didn't have time to look into them but...," he hesitates, "would you mind kissing me before i go?"

You blink, a bit startled but it sinks in quickly that Sans is trying to say goodbye to you and that this would be your only chance. You still weren't entirely sure if the amount of affection you felt towards Sans would count as love, but he was precious to you. If only your soul was in better shape... You wanted to feel the confidence and reassurance that your place was at his side.

He looks nervous, sweat beading on his skull and you smile to alleviate his worries.

"Of course," you say softly and his mouth tilts upwards tentatively into a smile. Relaxing your grip on his back, you rest your hands over his shoulders and lean forward; his pupil flaring brighter in response as you press your lips against his teeth.

He trembles as you place gentle pecks on his face, his teeth and chin, a teal blush tinting his face. The surfaces your lips touched were smooth and warm, not like anything you expecting. Slightly curious, your part your lips slightly and lap quickly at his teeth and Sans jerked back in surprise.

"S-sorry!" Did you overstep here?

"can--can...i...?" He seems at a loss for words and then simply parts his teeth. It shocks you a bit to notice that his teeth weren't perfectly straight like you had expected. Sans had rather prominant canines when his mouth was open and the bright, glowing teal tongue that appears causes you to pause.

Was his magic doing that? 

You raise your fingers to his parted mouth and the skeleton gently laves the glowing appendage over your digits. You shiver a bit from the sensation, the ectoplasm was cool and left your skin tingling. It was also slick but not unpleasantly so. In fact your stomach did odd flips at the texture. A small bit of glowing liquid is left on your fingers and it slowly began to disappear.

Your eyes raise to look Sans in his glowing eye and its so very clear that he is expecting a negative reaction that it hurts your heart.

Leaning forward, your lips part and you gingerly lick at the glowing tongue, tasting. It is slightly sweet and the startled groan you bring from the skeleton sends fire shooting down to your loins.

Closing the rest of the gap, Sans's glowing tongue breaches your mouth and begins to thoroughly explore.

"Hnmm..." You hum pleasantly as your tongues curl together slowly, his cool appendage warming from being in touch with your own. Glowing blue liquid trails down your chin, but it is so sweet that you don't mind.

Sans lingers and takes his time; heat coiling and pooling into wetness between your thighs. This feels so nice, like nothing you have experienced. When he pulls back from the kiss, a small trail of ectoplasm trails between your lips and his tongue before it breaks.

There is a smoldering, nearly predatory look in his eyes that makes you want to ask for more, but you refrain as he cups your face between his hands, the fiery blue pupil taking in your features.

Like he was trying to memorize it...

With a sinking feeling, your eyes widen. It couldn't be time, already...

"i have to go, _____." He murmurs, voice husky and deep from your previous actions. You begin shaking your head faintly in denial and his expression gentles.

"i won't let Frisk get through." Sans promises and he opens his furred jacket to extract the dim and broken soul. His only has the one chip on it and when the skeleton holds out your soul; you take it with a confused expression.

"i can't risk it..." He breathes and his smooth cheek nuzzles against yours affectionately, "i love you, _____. i will fight for you."

Words get caught in your throat. There is so much you want to say at that moment. You wanted to tell him that you suspected that you loved him back, perhaps you were more like a monster than a human now from what he had said of their nature. You wanted to beg him not to go. To stay here with you until the reset.

But you can't say anything because you are crying too hard. You cradle your pathetic excuse of a soul to your chest as he lays you against the wall and presses his teeth against your forehead in a 'kiss'.

Your eyes jerk upwards to meet his and there are also those bright blue tears pooling from his sockets. He gives you an understanding smile and before you know it, you are watching him leave.

Hyperventilating now and gasping between breaths, you try to get yourself pulled together. It was understandable to be afraid in the end.

But you couldn't let him be alone when everything ceased to be.

You had thought before that you had nowhere to belong.

But you knew now, that your place was by his side.

You struggle to your feet and immediately are knocked off balance by the entire floor shaking after a foreboding rumble.

Sans was fighting.

You...you needed to do something! But what...? You struggle up the stairway but have to stop a few steps from being at the top.

Because in front of you is a golden flower with a frown on his face.


	11. Chapter 11

**Summary for the Chapter:**

> Let me get this out so I don't start a mob; THIS STORY IS NOT OVER!!!
> 
> ....don't kill me. I promise much sinning. X'D

"W-Well, Howdy there!" The flower trilled, looking less tense than it had before, "this is DEFINITELY interesting! What is another human doing in the King's castle carrying around a shattered soul?"

You frown. That voice nags at the back of your consciousness. You are pretty sure that you have heard it somewhere before... Staring at the flower's face; you realize something is off. Much like your vision blurring when you saw Frisk at the ruins, with two red souls close together; there is a complete absence of a soul here.

Testing the waters, you take the next two steps to be level with the smiling flower, "what is a talking flower doing here?" 

It's expression darkens, "it is pretty rude to answer a question with another question."

Very suspicious. And your instincts are screaming that you know that voice from somewhere.

"Have we met before?" You ask, which causes the flower to smirk.

"I am positive we have never met before!" It answers with an knowing undertone. You blink and frown. It had made it here without being killed. So it possibly knew...

You didn't have time for this.

"I need to find a way to stop Frisk or this will be all over." You told the flower, whose face contorted and you were suddenly whipped off your feet and hit the floor pretty hard with a pained cry. The flower was right in your face and entirely too close to your soul for comfort.

It was trembling and it's expressions...or faces were flickering quickly as if in panic, "what do you mean 'over'??"

One of the faces that flickered over the front of the flower had you tensing in recognition. A small memory came back to you. You had been here before, a very long time ago. There had been yellow flowers everywhere as Gaster introduced you to the monster that was the donor for your genes. The lullaby you had sung Sans to sleep with had been to the tune of a music box belonging to their child...

"Asriel?" You breathe, eyes widening. The flower grew still, staring up at you in complete shock. The rough vine it had wrapped around your ankle loosened its tight grip. Slowly, the generic face morphed into the one you were familiar with.

"H-How did you know it was me...? Who are you?" The voice was timid.

"I am Doctor Gaster's experiment. I remember you from when he took me to this castle to meet your mother."

The child's face stared up at you for a moment before Asriel spoke, "you said that this was going to be over."

He had believed you. Probably because W.D. Gaster's name carried weight or perhaps he had recalled the brief meeting as well.

"If what I understand from both Sans," Asriel made a 'pft' noise at his name which causes you to frown, "and from what I know happened to the Doctor; this part of space and time had been fractured by their protect. This is where they all cross over and as the natural order of things...it will snap back."

Asriel's face looked terrified, "l-last time? No more resets?"

"No." You answer grimly.

"So if Chara resets right now?"

"Who is Chara?" You ask and the flower makes a noise of distress.

"They were my human sibling. They fell after your...meeting." He was unsure of you, but was talking. You didn't know if it was the shock of your sudden appearance in the timeline or the knowledge you had about the 'resets'.

"But Sans called them Frisk...." You pause and things just line up in your head; a clear path from 'a' to 'b' that the Doctor tried to tell you about when you were young.

"The two red souls..." You murmur and you get up. Asriel doesn't try to stop you, perhaps too numb or scared to try. But the fallen prince did yell after you.

"What you you doing?!"

There might be no more time to delay. The loud explosions from the Hall make you run as fast as you could, despite that pain you were suffering. You clutching your dim and cracked soul to your chest as you rushed forward.

That shining point from 'a' to 'b'.... You understood it now. It was not a single child. There was one that that was innately 'good' and responsible for timelines that ended with everyone escaping. And the other that had violent intent...

If you could reach the child that was being suppressed...

You run into the Hall of Judgement, panting and your heart drops at what you see.

It was like time had slowed down; your breathing and heartbeats raging in your ear drums. Your chest aching with pain as your eyes widen.

'Frisk' was in mid jump; the dull, bloody knife held before them. Sans' was staggering on his feet; his eye sockets closed as he gave into exhaustion. The huge glowing skulls around him were at the ready, like he hadn't slipped off until a moment ago.

Seeing Sans about to be murdered and ultimately fading from existence altogether...

Filled you with DETERMINATION!

"SANS!!!" You screamed and the soul you held flared with intense light. Sans' body jerked and his gaze snapped open in time for him to see 'Frisk' bounce off of a shield that protected him from what would've been a killing blow. The child's face twisted into a surprised and annoyed expression that didn't fit their face.

Your wide eyes took in the soul within your hands; your left eye ablaze with aqua. It was trembling under the force of its' own powerful light; vibrating dangerously and there was faint 'chink' noise that threatened.

Moving your gaze from the dangerously trembling soul; you could see one option hovering before you.

{SAVE}

The word was sending off waves that distorted the room in front of you. The Hall of Judgement was fractured into infinite mirrors. In some of them, Sans was greeting Frisk with warmth, in more they were fighting, and in some; the child was sharing a secret code.

You couldn't see the Sans of this timeline anymore; but you could hear him calling for you. Telling you not to do it. To stop.

Before you was 'Frisk' with two very clear double images. The one holding the knife had a vicious expression and the other had tears tracking down their face.

Behind them, without anyone else being able to see... In multiple fragments of the infinite timelines is W.D. Gaster.

Ah...

You get it now.

The button blurs in his presence, some of it was now Wing Dings.

{S A V A E L L}

Save all...

"Sans..." You whisper, not sure if he could hear you, "I do love you. I want you to know that."

You could feel it now. The clear connection that your soul had made with his.

Chara's eyes widen and a {RESET} option flashes before them as you smile sadly. Frisk's eyes raise to meet your's and you nod.

The true human child who fell down broke free from Chara in time to choose to {SAVE} at the same time as you reach forward.

Both your DETERMINATION and their's sync together and the {RESET} option crumbles.

Your eyes shut in resignation, a few tears falling over your gently smiling lips.

The battered teal soul you held cracked loudly and shattered, the pieces falling through your parted fingers.


	12. Chapter 12

**Summary for the Chapter:**

> This chapter is short but full of the warm and fluffies. <3
> 
> Also, please follow me on Tumblr. <3 The story isn't caught up there, but I would love the company of my fellow sinners.
> 
> http://mercy-run.tumblr.com/

You had expected pain but instead; all around you is silence. Frowning, you open your eyes to look around the Hall of Judgement with a confused expression. All of the timelines were gone and it was now in one piece; but everything was unnaturally still and silent. Sans was frozen in place from twisting in your direction across from Frisk where he had fallen asleep. One of his hands were stretched out towards you. Frisk himself was utterly still; but you knew Chara was gone from them as the knife was in mid-fall and a single tear had halted halfway down their face.

This timeline was frozen. Did it not work? Did you and Frisk not have enough DETERMINATION?

Your eyes move when something shifts in the corner of your eye and your gaze rested on W.D. Gaster. He was not as you remember him; a distinguished scientist that kept his lab coat in neat order. The Monster now had a warped face and seemed to be melting; though he kept his form.

"Doctor..." You murmured, unsure. The scientist brought his still elegant hands in front of him and began to gracefully sign in Wing Dings.

-I am very proud of you, _____. I never knew that you would exceed my expectations in such a way.- There was a soft smile on his warped face.

You tentatively smile back, "...what is happening though? Everything is frozen."

You watch his hands carefully sign.

-The timelines are converging and the {SAVE ALL} function is drawing all of the hopes and dreams from each to bring your wish into fruition.-

"Will it be enough?"

-Certainly. But it will take a bit because there are thousands of timelines to account for.-

Thousands... Sans had fallen through not hundreds, but thousands of timelines. You wonder how your soul had survived this long.

"Am I going to die, Doctor Gaster?"

-Do you want to die, _____?- Gaster signed with a soft smile. You shook your head frantically.

"Of course not! I want to stay here with Sans!" You said, tears springing to your eyes, head lowering to look at the dust on the floor from where your soul had dissolved. A finger underneath your chin made you flinch and you looked at Gaster. The monster had hurt you in the past, after all... He withdrew his touch and began to sign again.

-Then are you willing to settle on a weaker soul and less connection to the physical, but more with the magical?-

You swallowed, eyes widening.

He was asking if you wanted to be a monster.

"Is that possible?"

A warped smile, -Only if you want it badly enough.-

You did... It didn't matter if your soul was weaker. Your soul had always been weak. As long as you could stay with Sans, nothing else mattered.

"I want to stay with him." You stated firmly.

-Very good, child.- He signed, -Then are you prepared now? To set everything right and leave your humanity behind?-

"Yes," you breathed. This had gone on long enough.

-The timelines are amassing. I will guide their extra strength and my own soul to break the barrier.- He signed, causing your eyes to widen.

"But..." Gaster takes your hand and you allow it, staring silently.

-I have existed long enough. I am satisfied. Could you tell Sans that I am sorry and that I thought of him as a son?-

You nod.

-Farewell then, ______-

"Goodbye, Doctor Gaster..." You whisper and the monster fades. Warmth floods your chest and you know that your magic was being directed inward to stabilize your new soul.

The soul of a monster.

Time abruptly begins to flow and Frisk's tear falls; Sans yell echoing through the Hall of Judgement. The 'x's on your skin begin to blink out of existence as one by one, monsters begin to appear suddenly.

Sans' glowing teal eye stared at you in puzzled way before taking in the new arrivals with even more confusion. All of the minor monsters are first, Greater Dog and Lesser Dog barking at each other in joy, cries of Monster Kid calling out to Shyren. Frisk is beaming now, which captures the skeleton's attention.

You smile as Frisk runs up to Sans and hugs him. If this wasn't such a precious moment, you would begin laughing at the incredulous expression your bond mate was wearing. You knew now why Sans had been so sure before. You could feel your connection, sure and strong.

One by one, the stronger monsters followed. Grillsby, Muffet, Alphys, Undyne, Mettaton.

"BROTHER!" 

You smile as Papyrus rushes to pick up both Frisk and Sans; whose sockets fill with relieved shining blue tears.

Toriel materialize in a sparkle of dust and...

Shouts of happiness, hope and relief rise up as Asgore walks into the hall of judgement holding Asriel, just as you remember him...

"MY CHILD!" Toriel shouts and she rushes towards both of them and pulls both into an embrace. Asgore looks startled but pleased at the same time.

Everyone is so caught up in excitement and happiness that you feel both warm and alone. A small tug on your sweater has you looking down and an unfamiliar human child staring up at you in confusion. Blinking in surprise; you raise your eyes to see five other humans circling you, ranging from children to young adults. They appear dazed but relieved.

The rumbling of voices in the hall suddenly quiet down and you look away from the six humans to find the royal family standing quietly; staring and smiling at you. Toriel was smiling warmly; her hand in Asriel's.

"Asriel told me that this is your doing, child. Is that true?" She asked in a soothing tone.

You hesitate and nod.

"Then, is it finally over?" She questioned timidly. Your eyes seek out Sans in the crowd; finding Papyrus unwilling to put either him or Frisk down. His whites met yours with the same question, tension on his face. You smile at him.

"It's over." You confirm and the cheer that rocks the Hall of Judgement is enough for you to know that everyone now knew what Sans had been carrying alone for too long.


	13. Chapter 13

**Summary for the Chapter:**

> Hey everyone! Please take the time to read this, I will appreciate it! <3 First of all; this may be my last update before we go into Christmas Eve and Christmas Day. Whatever you sinners celebrate around this time of year or even if you don't celebrate at all; I hope that you all stay safe and well; be happy and keep sinning. If you do celebrate, have a Happy Holidays! I want to take the time to thank every one of you that is following this story and enjoying it. You are amazing and I adore you! You keep me filled with DETERMINATION!
> 
> Also; this story may begin to sin in a way that some of you may dislike; so I want to put a warning forth just in case it isn't your cup of tea. If you quit reading here; I will understand! The rest of us will just be in the last and worst tier of Hell. ;) Our character is going to have a slight transformation leaning towards Tori's genes and since it is now possible, Sans is going to be a Daddy. I don't know how long it will take me to get to that point, but it will eventually happen.
> 
> Keep sinning everyone!

Undyne's sudden cry silences the Hall instantly, "Your Majesty, the barrier is gone!" The royal family are looking at the aquatic monster with wide, surprised expressions. All of the humans that had been previously sacrificed for the barrier are crowded together anxiously. All things considered, you understood why they were afraid. Had they also had the reset ability like Frisk? Or was Frisk a special case....

A delighted chuckle escaped the Queen and you look back to her, "oh my; you ended everything and freed us as well? But... How did you get here, dear? Did you fall down as well?"

That...made things more complicated. Gaster had blown a hole in space and time; so perhaps memories of him didn't return to the other inhabitants? Sans, yourself and Asriel knew him. Alphys had also remembered him, and by extension, Undyne.

Asriel saves you from your predicament.

"Mother, she was Doctor Gaster's project. Don't you remember meeting her before?" The small child said with a soft smile. It was like saying Gaster's name had unlocked something, as whispers and murmurs started up.

Or was that because they had found out you were an experiment? Suddenly, you are frightened that you will be rejected, even though you now had a monster soul. Sans is at your side in a blink and he pulls you into his arms protectively.

You knew he had questions. That everyone probably did; but you were glad that he had responded to your anxiety so swiftly. His embrace felt safe and you knew he wouldn't put up with anyone messing with you.

"Oh...Oh my..." Toriel's eyes widened as she took in the sight of the short skeleton that she knew as Sans in her restored memories. Her eyes lingered on the way he was cradling you protectively, "are you two...perhaps...?" She trailed off, confused.

Sans offered the monster queen a fond smile, "she is my bond mate."

"B-But, isn't she human?" Asriel questioned in his soft and gentle voice.

"She is-"

"No." You don't mean to talk over the skeleton holding you, but you wanted to be clear about it. Sans' white pupils lower to your face in confusion.

"N-Not anymore..."

You lower your gaze as the royal family's confusion is too much to handle. Asgore clears his throat and Toriel exchanged a look with him.

"Perhaps we should discuss this at a later time." Toriel told you delicately and you nod, grateful. Asgore and Undyne begin aiding the other monsters to evacuate in a calm fashion and Toriel left to help the humans with Asriel trailing along with her. That was probably for the best.

Sans suddenly picks you up easily and throws a look at his brother and Frisk before leaving the Hall of Judgment back towards the Underground. Even though you have been sleeping so much, you feel suddenly exhausted. The adrenaline from the fight has gone. The din from the Hall quiets as he continues to walk until there is nothing but quiet.

Once the skeleton is satisfied with the distance, he stops; the white points of light fading as he stared down at you.

"i...i...saw your soul shatter.... ______? what happened back there?" To your alarm, tears began to pool in his sockets and you lurch in his arms to hung him; causing his arms to fly up to support your new position.

"Sans! I am fine, please don't cry anymore. It is really over, I promise." You pause as your knowledge of using your magic is limited, "can you call my soul out?"

He hesitates and then sits down so abruptly that you squeak in surprise. His phalanges gently caress your face reverently before he lowers his free hand to your chest. As he slowly draws it away; your new soul easily heeds his call and appears.

It is whole and shining that same soothing teal that you associate completely with Sans. You feel him tense and look up at his face; his sockets half lidded in a gentle expression before they widen in realization. Human souls did 'feel' different after all...

"you...this soul...," his whites train on your eyes, "you are a monster now?"

You nod with a smile. You tell him how you had seen all of the timelines and how Gaster had appeared.

"He told me to tell you he was sorry," you told the skeleton, "he said he thought of you like a son."

"where is he now?" Sans asked after letting that sink in for a moment.

"He is gone... For good...," you murmur, unsure of what you are feeling, "he is the one that took down the barrier."

You sit in silence for awhile; just letting your new reality sink in. Suddenly, Sans' shoulders begin to quake and you glance up at him to see a wide sincere smile on his face as nervous, but joyful deep chuckling echoes within him. You don't know why, but you begin laughing too and soon enough; both of you are under the mercy of nearly hysterical laughter.

It was over! It was finally over!

And everyone was alive!

It took awhile for Sans and yourself to calm down but when you did; you took his skull within your hands and pressed your forehead to his.

"I love you." You whisper gently and Sans holds you tighter as your soul slowly returns when his free hand curls around your waist with his other arm.

"i love you too, _______" His tone of voice makes you shiver, "stay with me?"

"Of course, I wouldn't have it any other way." You murmur and he nuzzled the smooth cheek bone of his skull against your own cheek softly.

"BROTHER! WE ARE LEAVING! HURRY UP; LAZYBONES!" Papyrus yelled down the long hallway. You couldn't see him from this far away and marvel at how much the younger skeleton brother's voice carried.

Sans chuckled and he releases you so you could stand up on your own. He reaches out his own hand once he is up and you take it. When you return to the hall of judgement, Papyrus and Frisk are waiting for you. To your surprise; Frisk runs up to you and takes your free hand, beaming up at you.

"Hey, Frisk. You did great back there." You tell them and they nodded. They began signing with one hand and even though it definitely wasn't Wing Dings; you understood them for some reason.

-Chara is gone. I am so happy we get to leave for good.-

"Me too."

"COME ON! I WANT TO SEE THE SURFACE!" Papyrus whines and Sans' grin is more happy than you had ever seen before. It was a nice change from the sullen and traumatized skeleton that had told you his secret in the darkness of his messy room.  
Your group finally breaks free of the Underground and you blink at the sudden flare of light. Slowly, your eyes adjust and the scenery before you renders your voice useless. The sun is rising, sending oranges; reds; and yellows shooting across the lightening sky. Knowing that it wasn't a cave ceiling above you but the true sky makes you feel infinitely small.

There is a forest with lush green trees stretched before you and what had to be a human city on the horizon.

You smile softly. It was so beautiful and warm up here.

As you stand there quietly with your hands linked with both Sans and Frisk; barely hearing Papyrus' loud exclamations; you are happy for once in your life.

This feels like the beginning of your journey and you knew that where ever it would leave you; you would never let go of Sans.

Your hand squeezes his lightly and he returns the gesture just as tenderly as your close your eyes and feel your steady connection to Sans deep within your new soul. It was finally over and you were ready to live your life by his side.

Where you belonged.


	14. Chapter 14

**Summary for the Chapter:**

> Hey, sinners! Christmas wasn't even over yet and I needed to write. No rest for the wicked. X'D

To say that the first reaction of humankind to the monster's presence on the surface was mixed would be an understatement. They had initially been met with panic and confusion. Over the first month; there was a lot of meetings with the leader responsible for this part of the world. Asgore and Toriel were absolutely polite, patient and understanding of any questions and Frisk was the most animated Ambassador you could ever ask for. You and Sans barely got to even see each other in the first 30 days as you were naturally a curiosity, along with Frisk and the other six humans.

They didn't have any memory of actually facing and being killed by Asgore; thank goodness. That would have hurt all of the peace negotiations in a devastating way. You also let everyone believe that you were human to avoid confusion. Into the second month; it was surprisingly Mettaton that most humans had come to accept. It was probably due to the fact that he looked like a robot and not like a monster at all; plus that personality...

By the beginning of the third month, it had become apparent that a lot of humans would not accept monsters at all. They were very zealous in their reasoning that all monsters were a threat to many things; their religions and their way of life. But it seemed like this world was a lot different than the time when monsters had been forced behind the barrier.

No humans had magic and they were so divided in their opinions that a war did not begin. The human in charge of this place said that monsters were welcome if they met certain demands. Asgore was still fighting on some issues that seemed pro-segregation; but at least you had somewhere to live with your new family.

You smiled at the memory; walking hand in hand with Frisk. Once Toriel and Asgore had heard your entire story; they had adopted you straight away. Despite your weak, protests you were so glad. Frisk and Asriel were now your siblings; Asgore your father and Toriel; your mother.

Sans had jokingly began to call you 'princess' and when Papyrus heard the news; he began calling you that as well.

That was when you gave up on trying to shrug the nickname. Once Pap got something into his mind; it was useless to try to change it.

It had only been three months since you surfaced so you understood that Sans had to run a lot of damage control between keeping his sensitive younger brother away from racism and advising Asgore in meeting.

But, it was still rather lonely. He had reassured you just last night that discussions were coming into their favor and you couldn't wait to finally spend some time with your bond mate.

Tugging at your hand drew your attention and you hummed questioningly; looking down at Frisk; who began signing to you.

-You stopped walking, _____. Are you okay?- The child peers up into your face anxiously. You swallow and wipe the perspiration from your forehead.

"I must have gotten too lost in my head. Sorry about that, sweetie." You say in a soothing voice and begin walking again. Bless the human, but Frisk was always keeping you under their watch. Maybe you should feel a little belittled that the child was looking out for you; but you didn't mind. Your family and both skeleton brothers were very protective of you after that ordeal in the Hall of Judgement. Sans especially. It had been three months though; and you had finally gained enough weight to be considered healthy. Been active enough that you could hold your own for an entire day without being exhausted.

Sure, you felt a little 'off' today; but it was probably just the heat. You and Frisk were on your way to the beach to meet Undyne and Alphys after all.

Their smile returns in full force and they happily take your hand and swing it in time with your steps as you walk. As you approach the beach; it became more crowded and some people called out to you both in greeting. There were a few glares but thankfully no one would act on their hate in full day light in such a crowded place.

"YO, NERDS!" Undyne yells; holding her arms out to Frisk who is running towards her full-tilt. She spins your sibling and holds them close as you catch up at a slower pace.  
"Hey, Undyne;" you smile in response to her toothy grin, "where is Alphys?"

"Over there; buying some drinks," she looked pleased, "always thinking about others, I am glad she is mine."

You smile warmly. Alphys and Undyne had bound each other together two weeks ago. It was a private thing to show your soul to another; but Undyne had told you they shared a rather lovely shade of green now. You were so happy for them both. Shifting the duffle bag from your shoulder; you help Frisk cover all of their exposed skin in sun lotion so it doesn't get burned.

As soon as you are finished; Frisk is out in the water with Undyne. You smile softly; knowing that they will be undisturbed since the former Royal Guardsman looked intimidating enough. Something cool pressing to your arm causes you to flinch; but your expression brightens when you see Alphys blushing and that the thing touching you had been a bottle of water.

You take it gratefully and down nearly half of it in one go, "thanks, Alphys..." You sigh, and rub the back of your neck where sweat tickled its way down.

"N-No problem, _______." She stutters back and her gaze finds Undyne and Frisk splashing each other in the water, "t-they look like they are h-having a good time."

"Yeah," you smile fondly as you watch them, "Frisk has been working themselves silly alongside Mother and Father. Asriel usually is able to draw their attention away enough to play but I felt like they needed a little bit more today."

Her expression tightens a bit but relaxes. It is a reflex she had that you noticed whenever Asriel was brought up. You knew she was the reason that he had been brought back as a flower without a soul but it seemed she had to mentally remind herself that things were okay now.

"A-Aren't you going to join them, _-______?" Alphys asked shyly. You frown a bit and shake your head before motioning towards them.

"I am feeling a little tired today, but you can if you like." You smile kindly at her flustered expression.

"W-Will you be okay all by yourself?" She asked; adjusting her tiny glasses. You smile and nod, shooing her towards her bond mate. Finding a seat in the shadow of a changing station; you sit down and lean your head against the cooled concrete. Seeing Undyne and Alphys spend time together causing a longing within you for Sans. You understood that he was really busy and knew that things were going well; perhaps enough so that he could be with you all day instead of just before you fell asleep.

It didn't make it any easier though.

The chatter of the beach is very pleasant; human and monster voices ring throughout the shoreline. Daylight rarely had any squabbles or serious altercations between your two species; so it was almost like monsters had an unofficial curfew. Night made humans that meant harm more bold. Sure; there were some pretty nasty words spoken and plenty of dirty looks. But nothing too serious during the day.

Sans had been teaching you how to use your magic and channel it; even though you couldn't really use it without 'outing' yourself; at least in front of any human. You didn't want to raise a commotion over what species you were.

Your thoughts fly back to your sessions with Gaster in the lab. One time you had tried to get away when your soul was still tethered to you. Some of his attempts at getting it to disconnect had been really scary....

The hotlands had been a new sight for you. No other monster had seen you in time to cry out for help before the tall scientist had plucked you off your feet, with a very unamused expression on his face.

You had curled up around your teal, human soul and had started shaking from the intense heat of the lava so near.

"----!!!"

A confusing wave of vertigo overtook you as your eyes flew open. Huh? Had you fallen asleep? Undyne was in front of you with a concerned look on her face; her soaked hand on your shoulder. It felt nice against your burning skin; no wonder you had dreamt of the hotlands. Had you gotten sunburn? The sun had changed position...

"Hey Nerd, are you alright?" The red haired monster asked in a softer tone. You blinked a little, vision hazing over. Frisk was lingering over the aquatic guard's shoulder in worry. You attempted a smile but winced.

"...d-did I burn...?"

Undyne frowned and then you find yourself in her arms; the world spinning briefly. You close one of your eyes when a sluggish trail of what you think is sweat gets too close to it.

"F-Frisk...?" You couldn't see them and needed to get your sibling back home safely.

"No worries, wimp. They are with us, we are going to bring you home. Hang in there."

What was going on? Her gait was a little intense; Undyne's long legs eating up ground so fast that Alphys and Frisk likely couldn't hope to keep up. Your lips part to tell the former guard to slow down; it couldn't be that bad.

But you choke and suddenly your mouth is full of liquid that tastes like copper. It trails down your chin and your eyes widen at the horror in Undyne's expression.

You're scared... That someone so normally unshakable has that expression. Your vision fades to static and your left eye flares with magic in response to your sudden panic. You can't see and your magic feels so unstable right now.

"SHIT!" You faintly hear Undyne curse and she is covering your left eye, bright blue streaming through the cracks of her webbed fingers. The jostling stops and you are simply cradled against the monster as she stuggled with her cell phone.

"SANS, GET TO KING ASGORE'S HOUSE NOW!"

She doesn't even wait on a reply; flipping the phone shut and she is running again. Everything feels like it is fading away... Is this what monsters felt? Before they turned to dust?

"A-m...," you cough wetly and she lets out a string of expletives that would put most to shame.

"YOU SHUT YOUR MOUTH! NOT ANOTHER FUCKING WORD!" Her voice is quaking, like she wants to cry. Tears well into your useless eyes and fall down your sticky face, which you are now certain is blood.

"DON'T YOU CRY, YOU DAMNED DWEEB. WE WON'T LET ANYTHING HAPPEN TO YOU! YOU HEAR ME???"

You fall silent the rest of the trip; suddenly too tired, in pain and frightened to fight against Undyne. A door is slammed open and you are suddenly; and very gently lowered to the floor. Undyne kneels in front of a very startled Toriel.

"I-I have failed you, my Queen;" Undyne's whisper is close and you hear your Mother cry out in anguish. You want to reassure her; but you can't seem to find the strength to speak. The familiar smell of cinnamon butterscotch pie and the softness of fur surround you and you nuzzle weakly into your Mother's arms.

"My child...Oh my child..." She murmurs shakily and you could feel her healing magic battering you repeatedly before she utters a soft sound of grief and confusion.

There is a sudden silence and the sound of your soul mate's thunderous voice tears straight through it.

"W H A T H A P P E N E D?!?!" He sounds ready to murder someone and though your Mother flinches back at the power in his voice; you reach out blindly towards him. In a blink; his blessedly cool touch is stroking over your face.

Toriel is the first to recover as you soak in his presence, "U-Undyne. Please report."

You could almost picture the former Guardsman straightening, "She was at the beach with myself, Frisk and Alphys. She fell asleep in the shade and when I went to wake her; she was really hot to the touch. She then began to bleed and I got here as soo-"

"That is enough," Toriel said patiently before her voice became confused, "Sans, I tried to heal her but she isn't responding to healing magic. Can you check on her soul?"

You are surprised that Sans does this immediately; the warmth and security of his bony fingers touching your soul makes you even warmer. He is normally very vocal about only him being the one to see it. Undyne's gasp makes you tense.

Was your soul damaged again? Were you dying?

"she's fine," Sans sounds both relieved and puzzled.

Your soul was returned just as gently.

"Could this be something unique to her circumstances?" Toriel asked quietly.

"it's possible..." Sans murmured, his caress on your face tender and worried. You can feel his strong, bony arms gathering up your body as gently as he could. You whimper in response and he presses his teeth gently to your temple.

"she's too hot," Sans told Toriel, who nodded.

"Let me get the shower running for you," your Mother insists and Sans follows her immediately.

"hey, _______. stick with me. i will take care of you." His rumbling voice reassured. You smile weakly; trying to find his face with your darkened vision. The sound of the shower starting and Toriel excusing herself before the door clicked reached your ears.  
Without removing either of your clothes, Sans carefully entered the bathtub and closed the door. When the luke warm water hits you, you gasp because it feels freezing. Sans curls up with you under the spray, his arms like a vise around your smaller body.  
Both of you are soaked in seconds and your whimpering ceases when you get used to the temperature and find comfort in it.

There is a few moments of silence before Sans speaks.

"i am so sorry." He murmured and his deep voice is filled with so much regret that you want to comfort him. Your fingers are able to snag in his parka and you tug weakly.

He doesn't laugh.

"you needed me here and i was off heeding Asgore's every demand..." He paused, "but if you could..."

His voice caught and he has to struggle with himself, "if you could just pull through...one last time. i promise you that you won't be lonely ever again."

He knew you had been lonely? Something in your expression must have gave it away because he is speaking again.

"yeah, i knew that you missed me. i could feel it in my soul. but i thought if only i could fight on one more issue...make one more change...that you would be happier and safer."

His fingers trail down your arm in a comforting gesture.

"but i got us a place together! only you, me and paps. i wanted it to be a surprise. i know you like it here with the kid and Tori but i thought maybe..."

You tug on his coat harder and he pauses, noticing you nodding with a small smile.

"you wouldn't mind leaving your new family for a lazybones like me?" His voice sounds shaky.

Shaking your head, you smile wider but then wince when the action causes you pain.

He chokes on your name and your body is flush against his, both of you drenched.

"i promise you i will be worthy of you from now on. i won't leave you feeling wanting ever again. just please...hang on for me... you are so strong and have overcome all odds." You can feel his powerful magic running along your body soothingly, "get through this and i don't want you to ever have to struggle again. i can be your strength and protect you."

The sound of water and the arms of your most important person makes your eyes ease shut; the world fading away.


	15. Chapter 15

**Summary for the Chapter:**

> I told some of you I was going to sin in this chapter but IT DIDN'T HAPPEN! UGH! I wanted to, but I realized it would be another chapter or two... Don't worry! We will get sin!
> 
> EVEN IF I HAVE TO WRITE A SMUT FIC TO MAKE UP FOR IT! I have an idea! I will run with it!

When you finally come to; it is to the sound of hushed voices. Cautiously; you open your eyes and to your relief and happiness; Sans' tender gaze is the first thing you see. His grin widens when he notices you are awake.

"hey there, princess. if i had a heart, you probably would've caused multiple attacks by now," he sounds amused and you smile in response to his teasing. If he was cracking jokes, everything was fine.

"Good morning, my child," Toriel's warm voice pulls your attention from the rare sight of Sans greeting you right as you woke up. She is smiling, but there seems to be a bit of tension in her shoulders. You glance in between them.

"'Morning..." You sigh softly in greeting.

"How do you feel, _______?" The Queen's tone sounds curious and a tad timid. Blinking; you take account of your body. The last thing you remembered was cold water battering your body as Sans held you tight. You had been burning from the inside out and bleeding.

But now; you felt surprisingly light; no fever or pain anywhere. Your connection to your magic seems stronger than before. Nothing seems to be wrong.

"I feel a lot better," you reply, "I don't remember much; but from within memory; this is the best I have felt in a very long time."

You search her expression but the tension hasn't eased. Jerking your attention back to Sans; you find him looking nervous.

"What did I do now?" You ask after a moment of silence. Surely it couldn't be worse than anything you faced in the Hall of Judgement. Sans starts to stroke the small of your back soothingly in response to your question.

"we are more worried about your reaction, _____. we should have anticipated this; you didn't do anything wrong." His deep voice is just as soothing as his gentle touch. Toriel takes out her hand mirror; looking shy and tense.

"It's just that you take after me just a little more, my child," Toriel offered the mirror and after hesitating; you take it and bring it up to your face. You notice right off that you have blunt, pearly horns that couldn't be more than two inches long protruding from your forehead.

"Oh..." You exhale and then freeze as something peeks between your lips. Curious, you part your lips and tilt your head back to see small fangs. Staring a bit; you then swallow and lick your lips nervously. Sans is watching your face carefully and there is a faint blue tint to his cheek bones.

"A-Anything else different?" 

"When I was changing you into dry clothing; you do have a small tail now as well," your Mother answered, squirming, "but otherwise; everything else appears the same."

You blink and slowly let your new appearance sink in, reaching back to touch the soft downy fur of your tail. Toriel and Sans are both tense now; watching you with open worry.

You can't help it; you burst out into relieved laughter that has them both jumping in surprise. Your entire frame quakes with it as your hands try to stifle the clear, ringing sound of your amusement. You know you shouldn't laugh, especially when they had so clearly been worried about you.

But you can't stop it and between giggles and deep intakes of breath; you attempt to explain why you are laughing to appease their confusion.

"I-oh god," gasp, "survive time and," hah, "space and you think," giggle ,"horns and a bit of fluff," wheeze, "is gonna traumatize me???"

There is a beat of silence and then all three are roaring with laughter. They are relieved and are now probably berating themselves for doubting how you would take this. Frisk burst into the room followed by a more timid Asgore and Asriel.

-You have horns! Horns!- Frisk signs excitedly and they hop up into your lap to touch them. You grin as their soft fingers run along the smooth surface of your new feature; the sensation tickling a bit.

"I am guessing all is well then," Asriel's gentle voice captures your attention and you smile at your brother.

"I'm fine!" You insist and hug Frisk to you.

"Thank goodness," Asgore's voice rumbles, "but weren't you two doing homework?" Both Asriel and Frisk pull faces but they obediently follow their Father out of the room. Your eyes meet the whites in Sans' sockets.

"Did you mean what you said?" You ask and he nods, cupping your face.

"Every word. Tori gave Asgore an ear-full when she realized he was working me to the 'bone'." Both you and Toriel chuckle at the pun. You can't stop smiling and you hug the skeleton.

Toriel clears her throat after a long moment and you part; Sans looking sheepish.

"Of course; with your blessing; Tori," Sans murmured, flushed blue. She looks stern for a moment before her gentle voice rings with laughter.

"Of course, Sans. As long as you bring her back time to time but..." You blink when she blushes a pretty pink, "I must borrow _____ for a little bit."

You exchange a confused look with Sans before he is ushered from the room by your blushing Mother. Shutting the door firmly; the Queen returns to her seat by your bed.

"Well... I never thought I would ever do this...but..." She is fidgeting and avoiding your gaze. What was up? She looked somehow embarrassed...

"Mom?" You question softly; unsure. She clears her throat and sits up straight and proper.

"Yes. Ahem. I believe that now that you are an adult monster; it is time for us to have 'the talk.'" She peers down at you cautiously.

You stare at the goat monster blankly.

"Talk...? What talk?" You are confused. Toriel is squirming now.

"Didn't Gaster ever...inform you on...eh...intimacy...?"

...He hadn't really. What was-OH! You flush crimson.

"Tori-Toriel! You aren't gonna talk to me about...sex and stuff are you??" Your voice is hushed and you swear the temperature in the room had shot up a few degrees.

"I am afraid I must, my child." She insists, still blushing. You swallow and look everywhere but straight at her.

"Now, see; child, as you are a female monster; you will have heat cycles roughly every three months." Her voice was steady now and your gaze jerks back to your mother.

"Heat cycles?"

You had bled monthly early in your teens and even though it had confused Gaster; they had eventually stopped after a point. From your understanding; that was more of a human thing.

"Yes, child," she replied softly, "in females; your magic reaches a peak in which you can conceive a baby during a three day period. During this time; you will feel extremely hot; to the point where nothing but your soul mate's touch touch could relieve the heat. But you absolutely must NOT have Sans anywhere near you during this time."

Your attention is fully on your mother figure now, "why?"

"W-Well if you have not been with Sans yet and do not wish to have a child with him; it is best not to take any risks, _______. The heat calls to a more base side of a monster; Sans wouldn't be able to h-help himself." Toriel murmurs and you are worrying your bottom lip with your new fangs.

"Can we even have a baby? I don't know how it works between...." You can't finish that sentence, you are sure your head is going to com bust. Just like Grillsby's.

"M-Monster magic can work in some interesting ways," she ends that in a cough. Disappearing into the floor sounds like a spectacular option, but you need to know this stuff.

"How do I know when I am getting close to going into heat?" You ask, trying to be 'adult' about this. Toriel seems to be relieved that you are asking something else than how to do the actual act.

"You will be unable to eat any meat. You will start eating nothing but fruit. In excess. When you notice this, find yourself somewhere away from Sans so you can endure the cycle. If possible, stock up somewhere safe beforehand with water. Perhaps ask Alphys if they can find a place for you." Toriel smiled softly.

"Will it hurt?" 

"H-hurt? No, child. But it is quite exhausting. You feel like you are on fire and you are well...aroused. It will seem to go on forever, but it will eventually end."

...This was a lot to take in.

"Anything else I need to know, Mom?" You ask after a beat of silence, nervous.

"Not at the moment, child. That is all that I needed to tell you." The gentle Queen smiled and you return it before becoming nervous.

"H...How do I go about telling Sans that I....," you pause awkwardly, "that I want more with him?"

"Oh!" She blushed before looking down into her lap, where her furry hands are folded, "that I can't answer for you, child. You must tell him on your own, in your own way."

You frown, feeling anxious. What if Sans didn't want that with you? You had only exchanged one kiss and that was before the Hall of Judgement. Toriel is smiling gently and opens her arms for you, which you are engulfed in after you press against her.

"Do not fret, my child. Sans is a good monster and would not turn you away. Just tell him what is in your heart." You both part and she winks, "now go pack your things. He is waiting to take you to your new home."

"Toriel..."

"Do not worry! Asgore and I understand your need to be close. Even though it has only been a short time, I consider you my daughter. This will always be your home."

You feel like her words are filling you to bursting with affection and you nod, releasing a few happy tears and hugging her again. You had a family, a home and now a new home with Sans and his brother. You couldn't ask for more.


	16. Chapter 16

**Summary for the Chapter:**

> I hope you have toothbrushes available, because this chapter is cavity-inducing. ;) I have tortured you guys with enough angst...for now.
> 
> Brace yourself for sin (for sure!) in the next chapter.

After your....enlightening and embarrassing talk with your mother; you had packed all of your belongings. You hadn't really accumulated much, so you just had two bags full of mostly clothing. Frisk, Asriel and Asgore said a cheery 'farewell' to you with Frisk making Sans promise to give them a 'short cut' to your new home when they wanted to visit. The short skeleton chuckled deeply and gave your human sibling a pinkie promise.

"ready, _____?" Sans' whites in his eye sockets were trained warmly on your face and you nodded; slipping your free hand into his before the air around you hummed with magic. The air around you smelled like ozone as your soul mate's magic whisked you from one space to another within a blink of an eye. You nearly lose your footing when you are suddenly within another house; Sans steadying you with a fond grin.

You had never really developed teleportation yourself. That seemed to be something Sans had gotten after all of the timelines split.

You barely have time to recover or even look around before you are whisked off of your feet by a tall, excited Papyrus.

"PRINCESS, YOU HAVE ARRIVED! WELCOME HOME!" His eyes take in your face, "DID YOU DO SOMETHING TO YOUR HAIR?"

You burst out laughing and Sans is grinning up at his younger brother, "bro, the horns." He prompts gently. Papyrus gasps and holds you at arms length, your feet dangling in the air.

"YOU LOOK JUST LIKE THE KING AND QUEEN!" He yells joyfully, taking in your features. You wiggle in his grip.

"Papyrus-" You gasp happily, "can I get back down? I am 'short' of afraid of heights."

"OF COURS-" He breaks off and he eyes you in horror, "DID YOU JUST PUN?!"

Sans is shaking with laughter, one of his phalanges reaching up to wipe a glowing teal tear away in his mirth as you beam at the frustrated skeleton holding you.

"NYEHHHH! WHY DO YOU HAVE TO DO THAT, PRINCESS?! I WAS HAVING A GOOD DAY!" He demanded. Your smile gentles and you reach out both arms for a hug.

"I thought cracking puns was a requirement of having you as a brother?" You ask softly. Sans freezes, eye sockets widening as he looks up at you. Papyrus' jaw has dropped, a heavy orange blush across his face.

You squirm, expression falling. Had it been too forward of you to assume you were a family?

Suddenly you are crushed against Papyrus' sternum and you are being spun around to the happy 'Nyeh heh hehs' of the skeleton.

"YES! YES! _______, I AM YOUR BROTHER! I HAVE A SISTER! YOU CAN CRACK ALL THE HORRIBLE, AWFUL PUNS YOU LIKE!" He sounds so happy and when he places you carefully back on your feet; there are sparkles in his eye sockets.

"I SHALL FIX US A LOVELY SPAGHETTI DINNER TONIGHT!" Papyrus declared with a flourish, "IN CELEBRATION OF YOU COMING HOME!"

Home... You smile happily at the tall skeleton and glance over at Sans. His expression causes warmth to bloom in your soul; his sockets half lidded and such a happy expression pulling his mouth up into a sincere smile. Papyrus' voice pulls your attention back to him.

"BUT FIRST, I MUST MEET WITH UNDYNE!" He happily states before walking across the wooden floor and exiting the house. For a brief moment, you glance around; noticing that nearly everything was made out of wood. This must be a cabin. Remembering that they had a similar house in Snowdin causes you to smile softly.

"pap is your bro now; huh?" Sans murmurs happily, "we will have to work out how many horrible jokes we deal out a day; or else he may short circuit."

He winks and you giggle; taking in more of the house. It really was a cabin, but much larger than the one the skeleton brothers had lived in underground. There appeared to be three bedrooms up the staircase. You could also see what looked to be a large and luxurious kitchen in the next room from the living room you were standing. Everything smelled of sweet cedar and it seemed the large amount of gold the monsters possessed was in high demand by humankind.

"do you like it?" Was the shy question and you return your full attention to your soul mate. His expression is anxious but the warm smile there tells you he isn't too worried.

"I do!" You insist and you put your bags down before you cross the distance separating you both and hug him tightly. His arms fly up and wrap strongly around your smaller frame.

"S-Sans, I missed you so much!" You can't help the outburst, words pouring forth, "after everything I just sort of accepted I wouldn't see you often. But I thought about you nearly all day and it hurt to be apart."

"shhh, ______. it'll be alright, nothing will tear us apart now," Sans' smooth hands run up and down the length of your spine, his deep voice rumbling against your body. You part with a relieved smile, eyes dry but your heart feels full.

"i bet you are hungry after your change. you should check out the rest of the house," he smiles at you happily as you kiss his teeth, "i will be back with something to eat."

"Thank you, Sans." You let go of him completely and he is gone in a blink. Smiling softly; you explore the kitchen first. Sans really must have let Papyrus go all out with the technology involved and the sheer amount of counter space available. The floor was carpeted whereas the rest of the house was made of sweet smelling wood. You took off your shoes and sank your toes into the plush carpet with delight.

How much had Sans and Papyrus paid in gold on this place? It also felt like you weren't in the city limits anymore. Glancing out a few windows, you found this to be true. However the city was still within sight, on the horizon to the east.  
You glance around the living room. Plenty of soft chairs and couches around a pretty sizable television. Picking up the remote; you flicked it on and grin in delight when it is on a cooking channel. 

Papyrus must be trying to learn from this program. You don't change the channel, simply turning it back off and you go up the stairs. There is a large bathroom at the end of the hallway with both a tub and shower. 

Peeking in the first room, you find it to be the master bedroom and you enter when you notice that the wall has a large poster with all of the constellations marked out on it. There is a telescope pointing out the large window into the back yard. Another bathroom is attached to this room and can only be accessed from here.

This must be Sans' room; you realize; touching the poster that showed off the stars with a soft smile. Leaving this room, the middle room is full of bookcases filled to capacity with a few comfortable looking chairs and a table. Deciding to leave that room for later; you find the last room to be a clone of Papyrus' old room; complete with the race car bed and pirate flag. There are a lot more action figures and the computer is new, but it is exactly like how it was when you had seen it so briefly before.  
Returning to the room full of books, your eyes scan the selection on one bookcase. There is a mix of human and monster children's books, monster history books, human history books, a ton of space texts, science tomes and some that looked really old. Upon reaching a part in one of the book case, there seemed to be a few missing.

Glancing at the table; your eyes widen slightly when you took in the subjects that were written on the books there. They were human health and anatomy books. You pick one up; leafing through it with a blush; your heart beating faster.

Was Sans...researching this for...?

A slight noise at the door startles you, your eyes jerking up in time to barely glimpse Sans before he had teleported away. Your face feels like it is on fire and you carefully place the book back down.

You could pretend that you hadn't seen him catch you reading his books....

No. You didn't want that. Toriel had told you to tell your soul mate what was in your heart. Steeling your resolve and courage in a few steady breaths, you descend the staircase to find Sans unpacking food that looked suspiciously like Grillsby's. Had the fire elemental taken his restaurant business to the surface?

His gaze flickers over to you, the only indication that he had caught you looking was the faint blue tint to his face and the slight strain in his sincere smile.

"Sans..." You begin but his nervous, deep voice cuts in.

"i got food from Grillsby's new joint. i hope you don't mind too much." His smile widens and you notice he is sweating slightly.

Ah, so it was Grillsby... 

He looked so nervous, the whites in his eye sockets darting everywhere but at your face.

"Sans...The books..."

He freezes and then sighed, muttering something about thinking he had been quick enough but the skeleton finally fixes you with a solemn look that startles you.

"do you think i am creepy now?"

Your eyes widen in response, "no, I don't."

His expression is flat as he takes you in carefully, "do you know why i was reading those?" The sweat beading down his skull is the only indication of his rising anxiety.

"Yes," you gasp out, blushing but you force yourself to go on, "but I am relieved!" You insist and his schooled expression breaks into one of confusion.

"...what?"

Speak from the heart, you remind yourself firmly. You take a shuddering breath.

"I want to be with you like that, Sans. I thought maybe you didn't, but I am glad that you want me like that too. That you are researching it is a huge relief to me. I've played around with different possibilities in my head, but I never thought to look it up. We have only kissed so far, but even back then; with everything that was happening...I didn't want you to stop!"

He is frozen in place; eye sockets wide enough that you fear he will somehow crack his skull but you continue.

"I love you, Sans. You are my soul mate. Of course I want to be with you intimately. I want to learn how to please you, how it feels like to be pleasured myself. You don't have to be nervous or think I will reject you. It's not creepy, it's considerate of you." That is as much as you can manage, your face burning.

His shocked expression eases into something tentative; veiled need burning in the whites of his eyes.

"you want me?" His deep voice asked lightly. You nod in affirmation.

"Yes." You breathe. His smile turned into something predatory that immediately caused a pleasant coil of heat to curl in your pelvis.

"then...shall we see how my studying has paid off?"


	17. Chapter 17

**Summary for the Chapter:**

> Here you go, sinners. <3 I hope you enjoy.
> 
> Growling! Sans is inspired by MrLewdBones NSFW audio. You can find that here: http://mrlewdbones.tumblr.com/testing

The dizzying feeling of Sans' magic coursing over your skin and being teleported at the same time brings a startled breath from your lungs. You laugh in delight when you tumble backwards into something soft, your soul mate bearing his weight to the left side of the bed. Sans grins down at your flushed face.

"Did you just teleport in mid-air?" You question almost breathlessly, "I didn't know that was possible!" 

"heh, great to know i can surprise you sometimes," he seemed really pleased, the whites in his eye sockets soft as he took in your expression. You knew what he meant; that shock in the Hall of Judgement was enough for a life time, not to mention you suddenly going slightly monster in appearance.

You suddenly feel nervous and Sans immediately picks up on it; "i can stop if you want?"

"NO!" You startle both him and yourself by the sudden volume and frantic note to your voice. You flush and touch your heated cheeks.

"S-sorry, I didn't mean to be Papyrus-loud." The lame joke causes the skeleton to chuckle in amusement, but his attention is trained on you very diligently.

"you look nervous, princess. mind telling me what is bothering you?" The gentle caress of the smooth, warm bone of his palm has you leaning into the touch.

"What if I do this wrong?" You ask and his expression is gentle.

"from my understanding, it is hard to mess this up unless you really don't want it to work," he winked and smiled, "if you don't mind; i can take the lead."

Hesitantly, you nod and reach down to the hem of your shirt to be stopped by a skeletal hand closing gently around your fist. There is a slight hum to the air and you breathed in the magic that you were more sensitive to now that you had changed. Timidly, you meet Sans' gaze; finding one of his eyes had gone dark; the other glowing a brilliant and beautiful blue.

"relax and let me take care of you." His voice has dropped an octave, the baritone washing over you before you smile and let go. The skeleton eases you back into the soft covers; a gentle smile on his face. His grip falls to your hips as Sans leaned over your smaller form to part his fanged teeth; his glowing tongue gently lapping at your bottom lip.

A soft moan escapes you at the tingling and cool feeling of ectoplasm before you part your mouth obediently to allow the magical appendage in. It is as sweet as you remember from underground, the light liquid seeping from your mouth and down your chin. Twining your hot tongue around Sans'; you suckle on it to swallow some of the glowing excess and to your delight; the skeleton lets out a low, soft noise of pleasure that rumbles throughout your body. He slowly tastes you, the appendage running along the top and bottom of your tongue, tickles the roof of your mouth; skims over your teeth.

"Hah..." You break away with a gasp, your face flushed from lack of oxygen and rising pleasure. Sans' glowing eye studies your face; taking in the glowing liquid leaking from your swollen lips and your glassy eyes as he withdrew his tongue. He leaned forward, past your face and you squirm when his tongue runs smoothly from the bottom of your neck to your ear. When he nips your lobe, you whimper in response and his teeth gently closed over your pulse point.

You hold still; the points of his fangs a very sure pressure against the vulnerable skin. Your hands fly up to grip at the fluff of his blue parka. Something about this... You weren't familiar with it, but it seemed to call to your instincts. You feel yourself becoming a mess as the skeleton slowly bit down until it hurt the barest amount.

"S-sans, nngh!" Your voice is trembling, but not with fear and suddenly your neck is released. Panting, you look into his blazing eye and you release his parka when he slowly pushed your top up; his skeletal hand flat and running up over every new inch of flesh that he revealed.

"so soft," his deep voice is breathy, "i can feel your heart beating really fast..." You lean towards him to allow the shirt to be pulled free and you resist the urge to cover your breasts under his intense gaze. It was incredibly strange, nudity used to mean nothing when you had been Gaster's experiment, but you feel like melting under the intense way Sans was staring at you.

The skeleton supported you while his other hand reached up to unclasp the bra you wore between two smooth fingers. Once your breasts were free; you laid back flat, blushing hotly. Sans' slowly took your exposed body in, pupil burning a steady teal glow.

"still okay, ______?" Sans asked in a low tone; his voice rough. You knew if you were to want him to stop, he would without hesitation. But you don't, so you nod in affirmation. His hand rests on the loose slacks you were wearing due to your new tail.

"shall we get this out of the way?"

You hesitate for one brief moment; staring into his heated expression before nodding, "yes, please." Your voice is still nervous but your soul mate smiles in response. The pants are pulled free and your white tail twitches in response to being free. Sans has both of your bared legs in his hands, slowly running his hands up and down your thighs. They tremble in response and he breathes out slowly.

"you're shaking," he murmurs, the single teal eye burning as he parts your thighs without any resistance. You swallow and finally do cover your face when the skeleton stares down at your pussy pushing against the fabric that has been darkened with your juices.

Sans fixes your legs over his shoulders and leans forward; one hand gripping your hip. He presses a hard digit into the wet panties before he trails it up; so slowly it is maddening. You cry out and kick when the tip of his phalanges strikes your hooded clit.

A growl rumbling in his chest has you trembling. Oh god, you didn't know Sans was capable of growling; but now that you had heard it... It would probably arouse you at the mere thought.

His cool glowing tongue laps your clothed core, applying delicious friction that you buck into.

"Hhhhnnn," the low keening whine drives him to hook a bony finger into the fabric, his magic carefully slicing the threads so he could pull the soaked panties from your core. As soon as it falls free, you uncover your face as you stare at Sans while he stared down at your exposed sex. Pushing both thumbs on either side of your lips, the skeleton pulled the flesh in opposing directions to reveal the soft pink layers marking the entrance into your body. You are throbbing and wriggling in his firm grip; a warm trail of fluid leaking from your exposed hole and running over your sensitive clit.

"so beautiful..." Sans growled lowly, his tongue licking along his fangs, "i can see deep inside of you."

"S-Saaannnss...." You beg and you weren't expecting him to answer your pleading with such vigor as a scream tears from your throat; his thick tongue delved into your sensitive folds, tasting you. His tongue is longer than you thought, or he made it that way because he bottoms out deep within you; his tongue fucking your untouched entrance. Whimpering, crying and begging; you fight in his grip as he maddeningly began to rub your aching clit over your hood. But his grip may as well be steel.

"Oh god, please....oh Sans! Ah!" Words spilled out of your mouth over the obscene squelching noises of your pussy overflowing with ectoplasam and your own juices. A deep, drawn out growl is your response and you scream as stars explode behind your eyes; your walls clamping down on Sans' tongue and sucking it in deeper; holding it like a vice.

He holds still until your inner walls unclamp and Sans pulls back with a satisfied and lusty expression, "so tight... feeling good, princess?"

You are still coming down from your high and you whimper as one of his hands comes up to tweak your hypersensitive nipples.

"Uwah...Oh Sans..." You moan, managing to force your eyes open. You blink in surprise when you notice a faintly glowing bulge in his shorts. You swallow and meet the skeleton's fiercely glowing eye. He doesn't say anything, waiting for your next move. You smile at him from your position, squeezing your knees slightly together to hug his skull.

"I want you, please..." You whisper.

His gaze is smoldering. You are going to burn up from his expression and magic. Sans reaches down and frees a very substantial glowing cock. You swallow, a bit nervous as you stare at the new appendage. It was the same shade as Sans' tongue, slightly translucent and was weeping glowing blue cum. There was a visible vein and the girth of the shaft made you wonder if Sans was overestimating you.

But you are throbbing, wet with your juices and Sans' ectoplasm and you want so much to share this with your soul mate. You meet his gaze and reach out your arms. Something soft flickers through the heat in his glowing eye.

"Please..." You whisper and he lowers himself so you can hold onto him. His grip slides down to your hip and he angles you up towards his pelvis. You close your eyes in anticipation for pain, because this had to hurt, right? But the gentle brush of Sans' cheek against yours have you opening your eyes to meet his glowing pupil.

"i love you so much, ________." He breathed, "i will make you feel so good...." His sentence ends in almost a purr and the coolness of the blunt head of Sans' magical dick rubs against your swelled clit.

You moan as he simply grinds against you, slowly. Before you know it, you are relaxed and soaking once more. His swollen head breaches you before you even realize what is happening.

"AH!" He is going slow, burying inch after inch into your aching pussy; his girth stretching you wide. Your walls are already jerking against his member.

"f-fuck..." Sans swore, growling. You were being stretched impossibly wide, but the slick ectoplasm is aiding him to sink in without it hurting you. But you are so full! You are certain you are going to be torn in two. 

But it feels so good and you don't feel like you will last; your insides trembling and clamping around Sans. His pelvic bone finally touches your ass as he bottoms out deep inside you.

"are you hurting?" Sans asked anxiously through his own pleasure, deep voice guttural.

You can't help it, you are desperate.

"NO! PLEASE SANS, OH GOD! MOVE!" You scream.

"with pleasure," he snarls and you are suddenly nearly empty before he slams back into you, your entire body rocking with the force. He gauges your reactions for the first few powerful thrusts and when you appear unharmed, Sans begins thrusting with abandon. You whimper and your walls close around Sans' cock in a vice grip.

He stops thrusting and holds still to watch with an awed expression as you climax.

"not yet..." He growls to himself, willing himself not to move as your ride out your orgasm. Sans wasn't done with the delicious feeling of your hot entrance surrounding him. You are super sensitive when you come down from your high and you whimper; feeling Sans' large cock throbbing inside of you. The cool appendage was now very hot.

"S-sans," you whisper.

"hold me tight, princess," he commanded and your arms wrap around his upper back before he is suddenly thrusting into you so fast and desperately that you are babbling and begging without conscious thought. Your walls are trying to clench around Sans but he is ravaging you so thoroughly and quickly that it can't happen.

"SANS! OH GOD!" You are going to fall apart. Surely you will die from this much pleasure.

Sans is close, his glowing cock throbbing and swelling within you as a constant growl rumbles in his chest. His cheek bones are stained teal and his tongue is lolling in between his parted fangs. Sweat is pouring down his skull.

"F U C K!" His pelvis slams against the soft skin of your buttocks. You toss your head back as he strikes a place within that has you trembling. He presses so deep inside you that you scream, clawing at his parka. His cock is squeezed in a vice-like grip and you are sucking him in deeper, jerking his cock.

Glowing blue liquid fills your insides and overflows, leaking down to tickle the tight pucker of your anus.

"argh, yes...." Sans' voice is nearly nothing but a growl, "milk me, oh god yes."

You spasm around his throbbing member and you feel your world fade.


	18. Chapter 18

**Summary for the Chapter:**

> Short, fluffy update for you all! <3 I was out running errands all day so I am pretty beat...and it effected my ability to write today; but I will get rest...soon...promise. ^^;;
> 
> Next chapter is going to be a mix of fluffy and sin. Then in chapter 20; there will be a significant time-skip for some pretty serious skele-sinning. I hope it doesn't destroy the pacing too badly.
> 
> Also, I am on tumblr and love to make friends! I won't bite you! Promise.
> 
> ....I will make Sans do it.
> 
> http://mercy-run.tumblr.com/

You can't quite find the motivation to move but when you do manage to open your eyes; you hear quiet voices downstairs. Blinking sluggishly; you take in that you had been cleaned of all the messy liquid you had expected to be drying on your skin when you woke up and that your clothing had been changed. You suddenly recall what Sans and yourself had been up to before you had passed out and blushed.

It had been good, amazing in fact. Incredible in the way that you hadn't died from sensory overload. And you had seen a slightly more primal side of your soul mate. Even through all of the growling and power Sans had revealed, not once had you been even the slightest bit afraid.

You had held his soul in your grip and above all; the skeleton had an unfaltering kindness and a deep well of love for his friends and family. Even though he had been through so much, the certainty that he loved you and wouldn't ever hurt you willingly was a constant.

You checked to make sure the large hoodie Sans had dressed you in covered you properly when you stood and exited the master bedroom. Peeking over the wooden railing; you grin when you spot Papyrus and Sans sitting on the large sofa in front of the television. It was switched onto the cooking channel from before but the volume was turned all the way down.

Now that you were above them, you hide your smile with your hands when you hear Papyrus' version of a whisper.

"Sans, are you sure the princess is alright? She has been sleeping for quite some time now." The taller skeleton loudly stage whispered to his older brother. This was the quietest you had heard him speak within memory. Your soul mate was kicking his skippered feet that dangled off of the couch with a happy expression.

"_____ is perfectly fine, pap. she just needs some extra rest from her changes," his voice was soothing; all traces of the unbridled, growling skeleton that had been ravaging you earlier. Calming your racing heart at the mere memory, you continue to quietly listen in to their relaxed conversation.

"Is she really my sister now, Sans? She said she was my sister but you say she isn't your sister, but we are brothers...?" Papyrus' stage whisper is strained and confused and Sans smiled at his younger brother patiently.

"you remember learning all about soul mates in monster school, right?" 

Papyrus looks like he is going to shout in excitement, but he contains himself enough to answer a hopeful, slightly louder, "yes!"

"well just like with Undyne and Alphys, ______ and I are soul mates as well. so she belongs with me and by association; is your sister." He explained and the taller skeleton's eye sockets sparkled.

"that is so wonderful, brother! i hope to be someone's soul mate one day too!" His voice is increasingly louder. A protective look flashes in Sans' glowing eyes but he smiles softly.

"just make sure they are as great as you." He insisted.

"Sans..." Papyrus drew out his voice in an admiring tone, eyes sparkling.

"but don't 'skulk' if it takes awhile." Sans winked and Papyrus's expression warped into one of annoyance.

"SSAAAANSSS!" He yelled, voice back to full volume as his older brother shook with laughter, the whites of his eyes lifting to meet your's when you failed to contain your mirth, laughing out loud. Papyrus twists around to look up at you.

"DON'T ENCOURAGE HIM, SISTER! YOU ARE ENABLING HIM!" He insisted. Giggling, you walk down the stairs, your hidden tail twitching from side to side in happiness. You were sort of glad it was hidden, it was kind of embarrassing.

"But you are smiling!" You point out, playfully.

"I HATE IT!" He swore, standing up from the sofa as Sans' gaze flickered between you and his younger brother. You spread your arms out in an open gesture, smiling widely.

"You can't hate all of it! Don't you like to hear your older brother laughing?" You did, you confessed inwardly. It was one of the loveliest sounds you knew; that deep, full bodied and sincere laughter.

Papyrus hesitated but pointed his index finger in the air as he found another point to argue, "BUT THE PUNS ARE AWFUL! HE HAS A LOT OF GOOD JOKES! WHY DOES HE ONLY TELL THE HORRIBLE ONES??"

Sans' gaze trained on you in interest; watching your interaction happily.

"Because it is endearing to hear you complain about something harmless and it is familiar. It is so awesome when you make the rare pun yourself," you smile as Papyrus thinks on this and the nods in understanding.

A timer goes off in the kitchen and Papyrus jerks to attention.

"I MUST 'SPAGHETTI' OUT OF HERE, DINNER IS READY!" He is in the kitchen before the pun sinks in and you glance over at Sans to glimpse his astonished expression before you both dissolve into happy laughter.

Dinner in your new home has no shortage of humor and laughter you discovered whilst eating dinner, noting the lack of glitter and happily offer your plate for seconds to your skeletal brother. He had improved a lot and you said so under the delighted gaze of Sans. It was warm and felt like a home; somewhere to finally settle next to your soul mate.

You had changed species, souls, and where you lived; but you were so happy here. 

"BROTHER! WE SHOULD TAKE ______ TO THE PLACE WHERE HUMANS KEEP THE ANIMALS THEY CAPTURE TOMORROW!" Papyrus suggested. You are confused and look to Sans for help.

"it is called a 'zoo', bro." He supplies and you chuckle.

"YES! THE ZOO!" The tall skeleton crowed joyfully and Sans could not deny him; even if going downtown meant more humans that may or may not like monsters.

"sure, bro," Sans murmured and he meets your gaze, "it's a date?"

You blush and nod.

"Sure! I haven't been yet. Frisk told me a lot about it." You agree. You help with the clean up and once things quieted down; Sans leads you back upstairs, holding your hand in his. Once the door is shut, his white pupils glow in the dim room as the skeleton takes in your happy smile.

"are you okay?" The concern throws you off and then you realize what he is talking about. Flushing, you swing your joined hands.

"Sans, I would've let you know immediately if I wasn't okay with anything you did, alright?" You reassure him gently. He smiles, fangs peeking through briefly in his relief.

"...i didn't scare you?" 

If you could melt into the floor out of embarrassment, you would, "q-quite the opposite, actually!"

He searches your face and then smirks lightly, relieved that you are well and that you had enjoyed what he had done.

"let's get some extra sleep," his deep voice washes through you and you happily curl up in bed with your skeleton, "pap will be waking us at the crack of dawn."

You press a kiss to his teeth and snuggled into his grip, "I am looking forward to our date."

"me too. i love you, ______."

"I love you, Sans."

Neither you or Sans had any nightmares that night.


	19. Chapter 19

**Summary for the Chapter:**

> HAPPY NEW YEAR, SINNERS! <3 Have some fluff with a touch of sin.
> 
> Get ready for the next chapter; there is going to be a time-skip!

Papyrus had woken you both at the crack of dawn; it was probably only by sheer determination that you managed to let go of a very sleepy Sans; who was muttering nonsense into his pillow; one socket barely open. You were whisked from the bed with a squeal that had the short skeleton immediately awake and sitting up before he had registered what happened.

"NYEH HEH, BROTHER! I HAVE YOUR SOUL MATE HOSTAGE!" Papyrus said, slyly and you were blushing as you frantically tugged Sans' large hoodie down to cover anything that might hurt the precious cinnamon roll's innocence.

"bro...wha...?" Sans' glowing pupils jerked from your flustered expression to his excited face.

"BREAKFAST AND THEN ZOO, SANS!" Papyrus demanded and you were taken so abruptly from the master bedroom and down to the kitchen that your mind barely had time to wake up.

Instead of spaghetti; Papyrus sits a stack of pancakes in front of you and you blink.

"No s-spaghetti, Pap?" You question past a yawn as you pick up the fork and begin to eat anyway. These were really good...

"I HAVE SPOILED YOU ALREADY, SISTER!" He points a spatula accusingly at you, "NO, PANCAKES THIS TIME. THE GREAT PAPYRUS LEAVES HIS BEST DISH FOR SPECIAL OCCASIONS."

You chuckle and swallow a bit of orange juice, nearly spitting it when Sans blinks into existence right next to you, already dressed and awake. He grins at you and presses his teeth to your cheek in a kiss.

"your clothes are on the bed, ______. a little warm for jackets, but i pulled the lightest one i could find that had a hood."

You smile in thanks, it was just a relief that you could hide the horns underneath a hood and the tail easily. Sans is dressed as usual in his blue furred parka, the only thing different that he is wearing sneakers instead of the pink slippers. Happily eating all of the pancakes on your plate, you listen to the light banter between the two brothers before you leave briefly to shower and get dressed in the master bathroom.

You pulled the hoodie up and find it to be baggy and long enough to hide your horns before you take the stairs two at a time. Papyrus is holding one of Sans bony hands, fidgeting excitedly.

"ready, princess?" Sans asked, his grin widening as you reach out for his free hand.

"Yes!" As soon as his hand tightens around yours, all three of you are suddenly just within an alleyway in the city. Papyrus can barely contain himself and you and Sans follow at a more sedate pace. You were only a block from the actual zoo and hadn't alerted anyone by teleporting. The tall skeleton ignores the dirty look that the ticket teller has on their face and you are one of the first few visitors actually inside.

"Maybe wait a little bit more until they actually open, pap?" You teased the skeleton good-naturedly.

"NONSCENCE!" He declares and you feel Sans' shoulders quaking in response from where you are still holding his hand. Papyrus' excitement is infectious because soon; both you and Sans are keeping pace with the tall skeleton at the different enclosures. There are a lot of animals here to learn about; and your younger brother reads all of the information about them from the signs in front of their habitats.

In fact...there were probably more species of animals from the surface here than there were different monsters from the underground. And from the information on the sign, most of these were local species and didn't even touch how many there actually were.

"SANS! ______! THERE ARE BABY ANIMALS OVER THERE!" Papyrus' eye sockets are sparkling, "CAN WE SEE THE BABY ANIMALS??"

"sure, bro," Sans answered in a deep, amused voice after checking to see how you were faring in the rising temperature, rearranging your hoodie with a fond smile. You both follow Papyrus into the building and find it to be a nursery of some sort. Papyrus takes note of the sign that had a sleeping baby animal with a warning to be quiet seriously; as he simply shakes and grins widely as he watches the zoo handlers take care of the babies. There are a few small smiles offered through the glass but most of them simply ignore all of you in favor of their work.

Gently pressing your fingers against the glass; you stare down at three bundles of spotted fluff, smiling as you read that these were newly born cheetah cubs. You motion an excited Papyrus' over and quietly speak to him while staring at the wild kittens.

"Pap, these babies are cheetahs. They are the fastest mammals on land. Remember seeing the adults outside?"

He nodded and grinned down at the sleeping balls of fluff.

"Would you like to hold one?" The voice is so unexpected, you jerk in surprise. One of the older zookeepers is smiling through the glass partisan, her weathered face kind.

"O-only if they can too," you insist after a moment and she grinned at you, while picking up one of the babies gently.

"I have nothing against monsters, child," she murmured and Papyrus is watching the older woman with wide eye sockets. Sans had walked up silently to watch the human carefully from behind you as the baby cheetah was eased into your arms.  
It was so warm and tiny. You smile as it yawns and shifts in your grip, tiny heartbeat thudding quickly against your chest. This is the first time you had ever held something so small. Even Frisk wasn't considered a 'baby'.

The wave of protective affection you felt was a bit surprising. Petting the fur there, you wondered idly what a baby between yourself and Sans would be like. Papyrus is vibrating with mute excitement in his desperation to not wake anything and you help the younger skeleton hold the cheetah kit properly.

After much cooing; you take it back from your grateful sibling before turning to Sans'. His grin was gentle but his expression morphs to shocked as you hold the animal out to him. After a pause, he reached out and took the baby animal into his grip. When it doesn't wake up and merely laid in his arms; the gentle smile that stretches Sans' face makes you feel such warmth.

The zookeeper allows you a few more minutes before she takes the cheetah back. Thanking her; you leave the nursery and Papyrus is immediately yelling about the experience now that it was permitted.

"I HELD THE TINY CHEETAH AND IT DIDN'T GET HURT! IT WAS SO SOFT, TINY AND FLUFFY!" He went on for a good half an hour until it was roughly around time to have lunch. You wait on a vacant bench while the skeleton brothers walk towards the food truck, having a debate between each other on what to order.

"...dirty monster supporter," you don't even bother to seek out who had muttered that; desperately trying to keep this day good. It was a constant battle to keep these comments away from Papyrus.

"...bet she is a pervert and is fucking them..."

Your face falls and Sans' glowing pupils find where you are sitting from where he is waiting with Papyrus, confusion in his gaze. You smile for him but it is rather weak and it falls when one of the people speaking blocks your vision.

"Hey, I know you can hear us. Want to answer that last question? We are curious to know," the male human leans closer to you, "are you a dirty monster fucker?"

You grit your fangs against your bottom row of teeth so hard it hurts and you glare up at the human from below your hood.

"Hey, its that person from television that came up with them. She probably doesn't know any better; we learned in elementary school that we had skeletons inside us. Doesn't realize how dirty fucking them is." He chuckled. Your eyes catch movement from the side.

Oh god, Sans and Papyrus had heard him; their sockets were wide and they were frozen in place. There was a dangerous hum in the air around your soul mate; his expression torn in between shame and the need to protect you.

Oh, you couldn't stand for this. 

"Wha...?!" He jerked back as your left eye burst into an angry flame of teal and your arm jerked to the side to send him soaring into his sleazy friends. In one smooth motion; you crossed the distance separating you and the two skeletons; a smile on your face as you took Papyrus by the elbow and Sans by the hand.

The shorter skeleton took the wordless gesture and you were back home in the blink of an eye.

"_______? WHAT DID THEY MEAN?" Papyrus looked dangerously close to crying and you offer him a smile.

"Don't listen to what those types of people say, Papyrus. They were just trying to drag us down." You knew that Papyrus had more knowledge on things Sans tried to keep him from because he had understood what they had been saying without having to ask.

"THEY-They called us 'dirty'..." Papyrus' voice had gotten quiet in his uncertainty and you smile, reaching up to him for a hug; which he returned after a moment. You kiss his forehead.

"There is nothing dirty about you and Sans, you understand? Nothing bad, nothing horrible, nothing of what they say, understood?" You insist, "they are just jealous that they aren't as great as you and are trying to make you sad."

Papyrus smiled down at you before straightening, "it-it is hard to be as GREAT as I am."

"Right?" You smile, your gaze going over to check on Sans; who still seemed downtrodden.

That wouldn't do.

"'I' may be a little dirty though, these clothes are soaked through with sweat. Come on, Sans." He makes a quiet noise of surprise when you begin to drag him after you, "don't wait up for us!"

Papyrus is happily placing your lunch out on the table as you close the door to the master bedroom behind yourself and your soul mate.

"_--_____?" The call of your name is pitched low and you tug him wordlessly to the bed without a fight and finally you are looking down into his face. He looked nervous, unsure of what you are doing.

You unzip his parka and your hands are underneath his white shirt before he can react properly. He gasped heavily as your one of your hands push the shirt up to expose his ribs and spine; your tongue running along the lowest rib. He squirmed, bony fingers fisting the messed up sheets as you sit up and let your weight hold his pelvic bone down.

"Sans, I don't ever want you to even let the slightest thought cross that numb skull of yours that I would ever be ashamed of you." You breathe and the teal blush over his face deepens as you stroke his spine.

"Ngh!"

"I love you," you whisper, pushing the parka and shirt off of the bed, "nothing about you is dirty or disgraceful. You are beautiful..." You push his shorts down and impatiently kick them off the bed. This is the most you have ever seen of him bare and nothing about him fails any expectations.

"____!" His voice is deeper than usual, the flush on his face making you smile as you firmly run an open palm repeatedly over his pelvic bone, the other skimming the base of his spine. The assault has Sans trembling; magic sparking in his left eye socket.  
Oh so gently, you cup his soul and run a tongue along the chip that hasn't healed yet; his raw scream of pleasure ebbing into an intense growl as his magic rushed through you in a powerful wave before fizzling out.

Grinning, you release the beautiful teal soul and stare down at Sans, who has been reduced to a mess; eying you tiredly.

"Did I get my point across?" You ask and he utters a soft growl that went all the way to your core.

"i will be paying you back for that." His expression softened and he pulled you close to his exposed body, "i will be paying you back for everything you do for me for the rest of our lives."

You smile up at him, "I wouldn't miss it for the world."


	20. Chapter 20

**Summary for the Chapter:**

> Heat part 1/2 ^_~ If you have requests; I wanna hear them! Comment here or message my tumblr.
> 
> Meet primal!Sans. <3

It was now roughly half a year since the confrontation in the Hall of Judgement that had freed the Underground from the thousands of timelines strangling it. While living among humans that were still racist was tough, at least nothing horrible had happened and you hoped that nothing would. No humans had dared to attack a monster outright and since your kind never traveled alone; it would be likely that they would not act on any urges of violence. Your own incident from the zoo had never been brought to authorities, so your secret was still safe.

Not that you were ashamed of being a monster, but you definitely didn't want to cause anymore trouble for your kind. Thank goodness that people gravitated towards Mettaton after exhausting you of interviews. Your story had been so generic that you were old news and virtually forgotten.

But things were rather exciting now; the leaves on the trees had started to turn colors and the air was cooler. Frisk had teleported in with Sans about a week ago and had explained the holiday coming up with excited signing.

"HALLOWEEN? WHAT IS THAT, HUMAN?" Papyrus had asked and Frisk had said it was when humans dressed up as monsters and either got candy or tricked people.

"sounds hilarious. i'm in." Sans had chimed in and now the holiday was in full swing. Everyone had wanted to go as a group; but your parents weren't able to take either Asriel or Frisk; so Sans and Papyrus had been gone for most of the day in order to celebrate the holiday with them. While you had been eager for the holiday last week; today you were just too tired and had to basically con Sans into taking your younger siblings out to have fun. He had shot you a concerned look and told you to call if you needed anything.

So you had just ended up reading quietly in the library; but you were pretty sure you had been on this same page for the last hour. The words blurred again and you blinked, squinting at the printed text; reaching into the bowl you had been snacking from.

...It was empty. Pushing your hair back from your sweaty forehead; you grab the mug nearby and down the rest of the water. Had someone messed with the thermostat? Closing the book and getting up; you carry the empty glass bowl and mug with you to double check the numbers.

Strange, it was still set at what should be a comfortable 74 degrees (f); but you were sweating rather heavily now from just that short trip. Maybe you were sick? Dropping off the empty dishes in the kitchen sink; you grab a bottle of water and an apple from the fridge, pressing the cool plastic to the base of your neck with a sigh.

But instead of relief, the touch of water makes it feel like your temperature skyrocketed instead. Your disappointed moan echoed throughout the empty house and you stared down at the apple in your hand blankly; suddenly no longer hungry.  
Maybe if you ran a bath...? You put the apple aside and desperately chug the water, but you might as well be drinking something room temperature.

"Damn it...." You huff; why wasn't anything helping?! Miserable; your gaze strayed back to the apple and you freeze. Mentally; you count back the months, frown and then try to recall what you had been eating. The glass bowl upstairs had been full of different types of fruit.

"Oh...oh no," you whisper. Frantically; you open the fridge and pick out a piece of lunch meat you had bought for sandwiches. You take a steadying breath and bite into it, but your stomach rebels so violently that you don't even get the chance to swallow it. Gagging and spitting it out into the trash; you breathe slowly for a few moments before panic grips you.

How could you have been so dumb?! Toriel had told you specifically what to look for and had even been right to the day on how many months you were to expect this to happen. She had warned you to get a safe place ready and stocked; and you had forgotten all about this.

The world spun around you and you swallowed; wincing at the dryness and hot breaths you released that seemed blisteringly hot. You grip the counters until your vision is steady, the heat rising and a spark of arousal igniting into something terrifying; sticky juices running down your thighs.

No...no...this wasn't happening. Why hadn't you remembered what your mother had told you? One hand releases the counter to clutch at your glowing left eye; the apple and some other things lifting from the table in a haze of teal.

You weren't doing that willingly; panic seized you and you are running despite how much your body is burning, bursting out of the house as the items crash to the tile when you are out of range. Your ragged breathing causes clouds of frost to puff in front of your face, but it may as well be summer out.

Putting some distance between yourself and the cabin; you shakily take out your cell phone. Who...who could you call that could help? You didn't want to bother your family, Papyrus or Sans. You punch in Alphys number, having to retry a few times because of how hard it was to focus.

"H-Hello...?" The dinosaur greeted nervously, "__--___?? It is a l-little late."

You can't call up coherent words for a moment, breathing raggedly as if you weren't getting enough oxygen.

"A-Alphys! Please...I-I am in...," searing tears roll down your face, "-trouble."

Her voice grew urgent and steady, "trouble? Where are you? I can get Sans-"

"NO!" And the line grows silent and you draw it away from your ear to check to see if you were still connected. You were and trembling, placed the phone back to your ear.

"You....you DON'T want me to get Sans?" Alphys sounded absolutely floored.

The world blurred and you fell heavily, causing the monster to call your name in worry.

"I...I messed up;" you sob into the grass; "...I...I...forgot..."

"Wait, you...oh no, are you in heat right now?!" Alphys shrieked and you wince from the volume.

"Y-yes..." You forced out, clutching your eye as the tree nearby splintered dangerously.

"Didn't the Queen warn you?! You were supposed to be here at the labs for it! I need to stabilize your magic. Where are you??" The rapid questions throw you off. You had expected the heat and arousal, but had never thought it would be this painful. What was this about magic?

"W..what...?" You look around; you were somewhere on the land near the cabin, Mt. Ebott was closer now than the city though, "...I don't know?" 

Alphys took a deep breath, "listen to me carefully, ______. I need a location, right now. Your magic is gravity-based like Sans, right?"

You whimper in response, thinking it sounded like a 'yes'.

"I need to get to you, _______, or you will-"

"....Alphys?" You whisper and look at the display. The call had disconnected. Frantically, you try calling back but you keep getting the busy signal. A loud crack has you springing to your feet, blurry vision jerking around and it is by the grace of luck that you avoid a falling tree, wincing as a branch snaps so violently that it cuts your face.

You tense as another tree groaned from pressure, your left eye ablaze with magic as fear grips you. Blindly running forward at full tilt; your lungs feel like they are going to burst. You are burning from the inside out and can't breathe. 

The cell phone in your fist begins to ring and you can't even read the display as you try to find some sort of shelter; hitting the button to bring it back up to your ear.

"_____!?" It is Alphys, the line wavering, "what is happening?!"

You scream as another tree breaks a mere foot away, faintly hear Alphys calling to you before Undyne's voice roared over the line.

"I NEED A YES OR NO! DO YOU WANT A CHILD WITH THE BONEHEAD??" The louder volume grounds your frantic mind just a little.

"Y-Yes," your voice is trembling, but you couldn't ask Sans to come just because you were in danger. You hadn't been able to ask if he wanted children with you and from what Toriel had said; he wouldn't have a choice if he was anywhere near you.

"I AM GOING TO CALL HIM, DWEEB! YOU STAY ALIVE, YA HEAR??"

"NO! He-He won't be able..." Your voice is lost as your mouth becomes so dry that your voice rasps and you gasp for air.

"IF HE WANTS A BABY, HE WILL GO AFTER YOU. IF NOT; PAP IS COMING FOR YOU. HANG ON!" Undyne's voice cut and you look around you with blurred vision, your left blind because of the glow of magic. Trembling you try to calm your magic down; but it just seems to make it worse as you grow terribly hot.

It is burning and you can't stop the pulse of magic. A tree cracks and you attempt to escape it; only to have a branch cut into your shoulder deep enough to tear cloth and muscle. You can't even scream; your voice lost as you blindly push it out of your wound and rush forward.

There had to be shelter or a clearing....something...

But this forest doesn't seem to end. All around you are the towering shadows of trees, the threatening snapping noises of your magic wanting to level the entire forest.

Tears sear down your cheeks as you gasp in air fruitlessly; the wound on your face and shoulder stinging. Was this going to be the end...? After sacrificing yourself in the Underground; you were going to die from forgetting this detail about your new life? You had been prepared to die then; you hadn't had anything left.

But here...

"s-s.a.." You barely get any warning before you have run out of ground and you are falling through the air, tumbling down.

Suddenly; bright teal fills your vision and your momentum is slowly halted before you are floating back up.

You barely make out a brightly glowing teal eye before strong arms close around you like a vice. The touch is so blessedly cold that you sob and gasp; pressing your face into the familiar fluff of Sans' collar.

The rumble of a growl is all the warning you get before you are pressed firmly back into the ground, your wrists caught in his grip. Your blurry vision is too hazy to make out his expression as he looms over you with his glowing eye.

"i'm sorry..." He growls before his fangs sink into your shoulder wound. You exhale a rasp that would probably be a scream if you had your voice before his cold tongue drags repeatedly over the wound.

You whimper and shift in confusion. It didn't hurt that much; even when he renewed his bite to draw out more blood only to soothe over the gash with his long glowing tongue. His magic was dragging over your body repeatedly and your vision clears enough that you can make out four Gaster Blasters hovering at the ready.

Behind them is a clear path of destruction that your magic wreaked...

Your shoulder throbs and you gasp at the soothing feeling of a thorough lick before he pulls back; running his tongue along his fangs that were covered in your blood. He lays one bony palm over your glowing eye; his own boring into your face.

There is a storm of different emotions flickering through his eye.

He was afraid to hurt you and couldn't control himself.

He loved you but hadn't known you wanted a family with him.

He wanted to lose control, but was afraid you would reject him.

You reach forward and yank him down to lick hungrily at his blood-stained mouth, grinding up into his pelvic bone.

That was all the permission he needed.


	21. Interlude

**Summary for the Chapter:**

> This is not a full chapter! <3 More like an Interlude/request from Yuubi. ^_^
> 
> Were you wondering about that phone call between Undyne and Sans?
> 
> Well, now you don't have to!

"PRINCE ASRIEL, I WOULD ADVISE THIS ROUTE NEXT!" Papyrus yelled loudly; looking down at the young monster. Frisk and Asriel had both decided to go as skeletons; much to Sans' and his younger brother's delight. Papyrus hadn't stopped 'nyeh heh heh' ing for a good hour at the masks and painted black clothing they both wore.

The gentle prince smiled up at the tall skeleton, "sure, Papyrus. Lead the way."

Even though night had fallen; none of the humans had caused any trouble for them. In fact; this seemed like the most accepting they had been. Perhaps it was the holiday... Sans blinked his eye sockets in surprise when his cell phone began buzzing. Were you calling him? He had told you to call if you needed anything.

He glanced at the display.

Undyne.

Picking up immediately, Sans held the phone to his skull, "what's up, undyne?"

"Sans, we have an issue."

He stiffened at her tense tone and his eyes met Frisk's. Both Asriel and Papyrus were shooting him confused looks.

"you guys go ahead; i have to take this." He told them with a smile and only when they turned away without any hesitation; chattering to each other happily did he teleport directly to Alphys new lab.

"FUCKING SHIT!" Undyne fumbled her phone and dropped it at his sudden appearance. Alphys was messing with her phone; trying to see if she had stored your tracking number in her contacts. 

Sans' tilted his head and was about to crack a joke before Undyne got over her shock.

"Sans, ______ is in heat."

If he had a beating heart; the skeleton would have sworn it had stopped beating at that simple sentence. His whites looked around the lab anxiously.

"why did you call me here then?" He asked in confusion. 

"Because she isn't here!" Undyne said anxiously.

"what...?" Of course you were here. Tori would have told you the basics of what all female monsters were schooled in before they fully matured. From what he remembered of the lecture from Dr. Gaster; every female monster went into heat and had to be helped by someone who could stabilize your magic. Scientists usually had the equipment to mimic a mate's hold over your core. It was synthetic and wouldn't help with the actual heat, but at least the monster would be in control.

"She's lost somewhere out in the forest."

No...no, this was the worst possible thing. His left eye socket erupted from anxiety and he growled lowly at the former Royal Guardsman.

"why are you still here? she has gravity magic!" His magic was humming and his fangs were bared in frustration. Didn't they understand the severity of the situation?!

"Sans, calm the fuck down," Undyne made a face at the magic sizzling in the air. Damn, she hadn't known his magic was this potent...

"N O." His voice was hollow and deep with a snarl, "H E L P H E R!"

"Do you want a babybones or not???" 

The question caught Sans off guard; the air becoming less heavy, "what...?"

"I asked her if she wanted your kid and she said yes."

You...you...

"she...she wants a baby?" His anger felt like it had been doused in water, "...with me?"

"OF COURSE YOU, FUCKING NUMBSKULL!" Undyne yelled impatiently. Later, she would think his incredibly shocked expression was cute, but right now she was worried about you. And damn her if Sans ever heard about it.

Sans' glowing eye seemed to be staring into some middle space as he thought. Gaster had all but left him to raise Papyrus on his own. And his little brother only came to his waist when their 'father' had vanished into space and time. He had experience with it...

But he was floored that you wanted a child with him... Sans had the blood of countless battles with Frisk (who he now knew had been Chara) on his hands. He had accepted his sins, that he had killed over and over; sometimes not in the name of judgement. But his own fear.

...He had never considered that you would want to start a family with him; but now that the notion was in his head, as a full possibility...

Sans wanted it. He wanted to take care of you and a baby, his baby. He wanted to make Papyrus an uncle.

He wanted to create something good with you. You had freed him from the nightmare of repeating timelines. The underground was now on the surface. Sans wanted nothing more to give you everything you desired.

His gaze focused on the tense couple and he grinned, "don't wait up."

Sans was gone in a blink and Undyne started as her girlfriend squealed happily.

"I ship that so hard!"

The sea monster chuckled, blushing a bit, "guess we should start making bets on the gender, eh, Alphys?"


	22. Chapter 21

**Summary for the Chapter:**

> I take no responsibility for any souls I drag to Skell with me in writing this fanfic. 
> 
> ....
> 
> I'M JOKING, COME WITH ME! WE HAVE COOKIES AND SPAGHETTI!
> 
> This chapter is rated R for Bone-R.

You exhale in surprise when Sans presses a hand to your chest and attempts to draw out your soul. Wincing, you are shocked that it doesn't even appear for him as it usually does. The tether is taut and unyielding; bringing discomfort. Panting; you desperately try to push any part of yourself against Sans' blessedly cool body.

"Ngh!" Why wasn't your soul cooperating with him? The pressure of his magic and the heat was making you delirious. Sans' sockets narrow; the left blazing with magic as he gives one last nearly painful tug before a feral grin parts his mouth; fangs showing.

"should have known your soul wouldn't come without a fight..." His voice is lower, nearly to the rumbling intensity that the skeleton often used when completely serious and running completely on emotion. The growling undertone sends vibrations down to your loins and you tremble as renewed juices seep down your thighs.

"F-Fight...ngn...?" You whisper and gasp as he raises your chin to angle your face just right for his glowing tongue to leave a cold path up your cheek; cleaning away the blood. Oh god, you were burning up from the inside...

"yes...like this; i could fuck you forever but your heat would never end." His feral grin softens, his teal pupil taking in your features, "i want to hear it from you..."

You shake and gasp; trying to piece his words together. What were you doing wrong? Why wouldn't your heat end? What did he...?

Sensing your confusion; Sans' gaze bores into your own and he touches the soft area below your stomach with gentle phalanges. 

"i need to hear it....please..." His deep voice is strained; a bead of teal sweat running down his skull.

Oh...

OH!

"i...i want to have..." You huff and Sans' expression is intense, "y-your baby, S-Sans..." It is effort to even speak. Happiness lights his expression before it is something wild again. He braces himself on all fours, lifting himself to hover over your body and a frustrated noise is choked off in your throat as you reach up to touch his face.

"you trust me, _______?" 

You are confused and frustrated once more. You feel like you had swallowed a flame, nearly angry enough to spit out some rather colorful language. You didn't deal with heat well.

"Yes!" Your voice is clipped and sweat is soaking your clothes. Tears burned down your tender face.

"then, know what i do is nessessary." He is suddenly gone and a cry of dismay tore from your throat. Weakly; you manage to shakily get to your feet and your eyes widen, pupils blown.

Sans is standing twenty feet in front of you, just outside the tree line. Four Gaster Blasters hover near him as he spreads his arms out; a challenging grin on his face. His teal soul with the single chip appears in front of his unzipped parka, pulsing in a steady thrum.

Your view is filled with four options, teal pulses from your chest but your soul isn't tugged free.

(Fight) (Act) (Items) (Run)

Oh--oh god...what??! You hadn't seen anything like this since you had saved Sans from Chara in the Hall of Judgement.

"S-Sans?!" You search his expression for any clue of why he had challenged you to a battle, but he waits patiently; glowing blue eye burning. You check all of your options except for (fight). You didn't want to hurt your soul mate, you didn't even know what he was doing! Shaking from the exertion, you choose to (run).

But the cliff is behind you. You can't escape.

Heavy pressure in the air alerts you and you spin around weakly in time to see all four of the Gaster Blasters spread their maws; charging up an attack with a rising whine of warning. You throw your hands up over your eyes as the light burned too brightly, whiting out your vision.

Searing heat flows past you and you shake; dropping to your knees in between the four deep grooves the Blasters burned into the landscape.

Your (Run) option shattered.

Frantically, you (Act), "S-Sans, please...I-don't understand!"

Sans' lifted a glowing hand, "you don't need to understand. Your soul on the other hand..." With a swift flick of his hand; you flew twenty feet into the air; gasping and struggling in the haze of blue magic. 

The (Item) option shatters, not really useful since you had absolutely nothing on you. Sans' glowing form rises easily to become level with you; burning after imagines remaining in the air seconds after he had disappeared.

His magic is intoxicating and even though you don't understand; you weren't afraid. You just wanted to understand! Tears float amid his gravity magic.

"S-Sans...please...I-I'm burning..." You plead. His expression twisted, pained for a moment before becoming wild.

"g i v e u p," the force of his voice rocked you as he flung a hand out towards you. The (Act) option faded. You didn't want to fight him, why was that the only option?

You refused.

The air became so saturated with his power that it was hard to breathe. Blinking, you realize that the sky looks off and as you continue to stare; you gasp. The night sky was breaking up; opening into a void. The air reeked of ozone and what you saw there was so utterly frightening that you felt sure you were going to die. You could see into the dimension that Gaster had traveled; shapes, texture and even the air felt wrong.

You were afraid of it. 

It was getting too dark; was this a black hole...?

"Sans..." Your voice is quiet and you squeeze your eyes shut to block out everything. Vaguely; you could feel the (fight) go out of you and suddenly, everything was quiet.

Your eyes opened to see nothing but utter darkness. You wanted to panic but a gentle light caught your attention. Gazing down, you see that your soul is floating free, pulsing in time with your heart. Arms reach around you and you moan in relief as Sans' pulled you against his body. His voice is gentle but the growl is still there.

"you did so well." He murmured and he turned you to face him. You blink sluggishly at his exposed soul and something occurred to you.

Your souls were pulsing in perfect synchronicity.

The soft forest floor was suddenly against your back as Sans returned this part of time and space to normal; but all that seemed to do was break your peaceful moment and you groaned as the sweltering temperature tore through you.

You knew now, as you had always before. Sans would never hurt you; but you couldn't take it anymore! Roughly your hands tear at your clothes, anguished cries falling from your lips. It was too hot! You were going to die!

Suddenly Sans hands are running all over you and you arch, looking up at him through a haze of fever. His grin is predatory and his hands leave you enough for him to shed his parka.

"i will take care of you, ________." He growled, "now that your magic knows i can protect any children i give you..."

Oh... Your mind messily pieced what he had done with his actions.

"S-Sans..." Too hot, too hot...

"i have you..."

Your body is suddenly bent, only your shoulders touching the ground. Whimpering; you kick your feet against the glow of magic holding your body this way. Sans made a few sharp gestures with one of his hands and your clothing is shredded.

The grip of his smooth hands wrings a cry from you. Sans was so blessedly cold everywhere. His left socket is blazing as he grinds his glowing blue cock against your drenched pussy; the swollen head teasing over your clit.

"Oh! Please, please, please!" You are begging, you don't care. This is what hell surely felt like and Sans was the only relief from the flames. Dimly, you realized that he had discarded all of his clothing.

"i will w r e a k you," Sans snarled and he canted his hips back before driving into your pussy in one thrust.

You couldn't help it; you screamed. Your senses were so confused. You didn't know whether it had hurt at all or if you were so relieved that you had vocalized it. Kicking futility against his magic restraining you, you whimper as he delved into you with obscene squelching noises; hipbone striking you as he bottomed out with each pass.

His cock was throbbing and swelling; and the coolness felt so good that you panted and writhed breathlessly.

So--So good... The soft fur of your tail quickly soaking in your juices and his glowing pre under his onslaught. He didn't seem to be tiring and you didn't care at this point if he somehow broke you in half. 

"...s-ssans..." Heat coiled dangerously in your pelvis; the walls of your core quivering.

"louder!" He growled, bucking into you hard.

"SANS!" Your pussy clamped down, jerking him in impossibly deeper.

"good girl...ah, yes..." His deep voice ebbed into a snarl as you came so hard that your vision blacked out. His cool and tingling ectoplasm filled your insides and dribbled down your thighs in copious amounts.

As you came down; you issued a noise of confused frustration when your body refused to lower its temperature.

A rather embarrassing squeak escapes your lips when you are suddenly on all fours.

Sans...hadn't pulled out of you for it; so you moaned as your sensitive walls gripped his cock in surprise. He is pressed up against your back; one hand gripping your hip; the other teasing a nipple.

The deep chuckle he issued near your ear was a terrifying mixture of terrifying and sexy.

"didn't toriel tell you how long this would last...?" 

What...? Your mind is too foggy to process memories and you moan as his fangs tease the soft skin of your neck before he bit down.

He is thrusting inside you again, the rapid pace startling a cry from you as your fingers dig desperately into the soil. His fangs are still buried into your neck and you can't move at all or Sans would surely make you bleed. The smooth fingers that were toying with an aching nipple lower to rub against your hooded clit.

You tremble and squirm; the tips of his fangs bringing blood before you are screaming from completion for a second time. His growling is muffled into your neck as he follows quickly, milking himself with your clenched walls.

You roll over, shaking and his glowing eye is staring down at you.

He is still fully erect.

"Sans, I'm going to die!" You insist, registering that your heat hadn't abated at all. He smirks, gaze smoldering.

"you will be fine, you are doing amazing," he chuckles and leans forward to lave his cool tongue soothingly against where he had bitten into your neck.

The memory of what Toriel said hits you like a sledge hammer.

"N-O, no no no! I AM going to DIE!" You insist.

You are pushed down, his hand covering your eyes so you can't see at all. His tongue breaches you and you sob.

"I-I can't...!" You choke. Was it possible to die from too much pleasure? From being to hot? Surely it was possible!

Your thighs quiver and you sob out a mixture of relief and frustration as Sans' laps up your release with a pleased hum.

"I can't do this!" You reiterated once you get your breathing back and start swearing when the heat STILL hasn't gone down.

Sans' expression is a mixture of tenderness and something primal.

"you will get through this," he murmured, "i won't let you die."

"THREE DAYS!" You scream at the top of your lungs, trying to make a point past the infuriating heat.

The fight is drained from you at the look on his face. His chuckle, you decide, is definitely evil.


	23. Chapter 22

**Summary for the Chapter:**

> People keep asking if I already know the gender and appearance of the baby....
> 
> Yes. Yes, I do. X'D

A soft groan escapes from your throat and you open one eye to stare up at the skeleton holding you. You didn't remember a good part of your heat cycle and that was probably for the best. There was a faint impression of you meeting Sans' desperation in his more carnal state; but you couldn't recall specifics.

But one thing was pretty apparent as Sans gently lowered your body down into the bath he had drawn for you. You wince even though it is luke-warm; you didn't want to feel anything remotely like heat.

You had never been this sore before. You were sure even your eyes ached. Your pale skin was littered with scratch and bite marks. Sans wasn't really well versed in healing magic, but he had tried his best.

If he didn't look so damn guilty; you would've threatened to hit him...as soon as you could move.

"i'm sorry..." Sans whites were trained on one particularly bad bite.

"Sans..." You sigh, looking him over sluggishly; "if you apologize one more time; I will hurt you."

He lowers his gaze at the threat and you shift in the scented water, "I'm not mad! Just...sore."

His teeth part; most likely to issue another apology but he catches himself and merely frowns. Sans looked so sad and guilty that it is too much to bear.

"So..." You murmur, testing your arms in the water, "...when do we know?"

Sans' eyes finally meet yours and he frowns a moment before what you are asking sinks in. Tentatively; he smiles softly.

"two weeks," he murmured, "we will be able to sense the baby if we managed to conceive this time."

You snort.

"Don't see how we couldn't have!" You joke and both of you erupt into laughter. It hurts, but it is so good to hear him laugh. And after that hellish heat cycle; you were glad to be back to normal.

A loud bang from downstairs interrupts the laughter and Sans is gone from the side of the bathtub in a blink; his left socket flaring.

Not a moment has passed before...

"SANS THE SKELETON!"

Oh.

My.

God.

You try to get up frantically. That was your Mother! Oh god, you had never heard Toriel angry and your stomach dropped as the water sloshed around you.

"I SHOULD BURN YOUR HOUSE DOWN!" She roared, "MY DAUGHTER! ON HER FIRST CYCLE! HOW COULD YOU?!?!"

"y-your majesty..." His voice was barely audible but he sounded absolutely terrified.

You take a huge breath to fill your lungs.

"MOM!!!!" You yelled and you could hear her rushing up the stairs, threatening Sans all the while before she opened the bathroom door. Her expression as she took you in made you tremble and recall that your mom was the queen for a reason.  
Her expression softened into sympathy and she was kneeling by the tub before you could take in the sudden change in emotion. You were pulled to her chest and the soothing smell of cinnamon butterscotch and fur enveloped you.

"I am so sorry, ______. Alphys called me this morning; I didn't know you had-"

"D-Did you let her finish?" You ask quietly and she blinked startled amethyst eyes at you before blushing.

"Well...she was stuttering rather horribly and when I had heard what Sans had done..." Her expression darkened. You placed a hand over her furry paw.

"Mom, don't be mad at Sans," you told her softly; "it was my choice to have him there during my...er heat."

Her eyes widened.

"W-what?"

"I want a baby with him. He came to me when I was in trouble," you flush, "I had forgotten all about it and was practically bringing the forest around here down."

Toriel was staring at you in shock, "but my child; you have only just begun to live yourself..."

"I know," you smile, "but...but when I learned that I could have his child; it kept popping up in my mind. I was so relieved when he showed up because if he didn't choose to come; it would have been Papyrus instead. That he came for me; he wants to be a father."

Toriel stared down at you in shock before her expression turned warm.

"SANS, YOU MAY LIVE FOR NOW!" She called out of the bathroom and there was a soft thud, like he had sat down hard.

"Oh dear..." She murmured, "I will have to apologize properly later. I fear I...rattled his bones."

"Oh my god," you snickered but winced. Her eyes took in all of the marks on your skin, all of the deep bites.

"Do you want me to heal you, my child?" She asked gently with a blush, "it looks like he wasn't gentle with you."

"I-I didn't mind, but yes."

The soothing touch of her healing magic had the soreness fading from your muscles; each scratch mark and bite receiving careful attention. When she tried to heal the one on your neck, you stopped her.

"Not that one!" You insisted with a flushed face and your mother smiled knowingly.

"I will leave it," she told you, "Sans must have done an amazing feat of magic to impress you if you want to keep his claiming mark."

"Claiming mark?"

A gentle blush touched her cheeks.

"Yes. It felt right and didn't hurt too much, correct?"

You nod.

"Biting such a vulnerable place and marking the skin is a dominance streak in the stronger monster. N-Not to say you are weak, just that your soul was pacified by his displaying and acknowledges that he can keep you safe."

Sans had been 'displaying' when he had initiated that battle? You were a little afraid what he was like in a real battle now...

"_______." Toriel called your name lightly to break you out of your stupor, cupping your cheek in her soft paw.

"I want to know the outcome in two weeks time. Please tell your family if we are expecting a new addition." Her expression was now delighted, "a baby... It has been so long. You returned Asriel to me and I can't express how truly, very grate-"  
Tears sprung to her eyes and you were mortified.

"No, mom. Please don't cry!" She took a deep breath and smiled.

"Thank you. Really, ______. I love you so much." She kissed your forehead and you smiled as she nuzzled one of your blunt horns.

"Do you promise to call?"

"Of course!" You swear and she chuckled, standing up and straightening her deep purple robes.

"I will go apologize to your traumatized mate," she said with a dainty blush and you chuckled as she left.

Two weeks... You really hoped that this heat cycle rewarded both you and Sans. If not, if definitely would not be for lack of effort.

Chuckling softly, you begin to wash off the grim from your skin now that you can move.


	24. Chapter 23

**Summary for the Chapter:**

> Short update! (I think I did two yesterday and one today thus far???) No sleep yet, omg. <3
> 
> There will probably be four more chapters and an epilogue after this, but who knows?

Over the next week; you tried not to get your hopes up just in case your first heat cycle didn't take. But it was really hard to not let your mind wander towards the thought of a child. Sans seemed to be in a similar thoughtful state, staring off into a middle distance sometimes and sneaking glances at you when he thought you weren't paying attention. By day three; you had broken down and asked him how you were supposed to know.

He had smiled brightly at you and told you that you would sense the soul inside of you and the sure definite sign that left no doubt was that you would lose the use of your magic. The skeleton explained that as the partner with an excess of advanced magic; it was his job to protect you as your own magic went to nurture the baby.

Sans encouraged you to start doing small things with your magic daily so you would notice any changes. You used your magic to do menial things, like flip switches, fetch dishes that were too high in the cabinets and to lift things that were too heavy. Papyrus had noticed the change immediately.

He caught you alone one day while Sans was out working alongside Alphys.

"SISTER! HAS SANS CORRUPTED YOU WITH HIS LAZY WAYS??" You nearly let your magic slip on the remote and blushed, lowering it back on the table it had been resting on.

"Oh! N-no, Papyrus," you didn't want to give him false hope either, but didn't want to lie, "Sans told me I should try using my magic daily."

His tilted his skull at you and placed a hand on his hip, "BECAUSE YOU DIDN'T USE MAGIC MUCH BEFORE?"

"Sort of," you answer with a warm smile. Papyrus was really sweet, you were so glad he was your family now.

"OKAY, SISTER, BUT DO NOT MAKE IT A HABIT!" He insisted worriedly. You nod cheerfully and he leaves to train with Undyne. What they are training for right now...you have no idea. You spend most of your days waiting anxiously by filling it with reading. Sans had so many books in the small library room and you passed your alone time with the tomes there.

Days pass by with no change and you get discouraged; so you just talk yourself down from any hope you had built up. You don't let it show to Sans that you feel a little depressed. After all; the heat had been horrible, but you could try again.

Distractedly; you put the book on monster legend down and get up with a sigh. It had been a very long day and you could do with some extra sleep. You yawn and stretch, closing your eyes as you made a motion to flick the switch off as you left.

You were in mid-step when you realize that the light didn't turn off. Confused and trying not to dare hope; you step back into the room and frown at the light switch. Staring directly at it; you make the same easy gesture in the air.

Nothing.

Your heart was thudding and you swallowed, trying to contain your excitement. One more time, you had to be absolutely sure. You concentrated very hard and tried to release your gravity magic with the usual ease.

But it was like it was shut off. Not in a horrible way.

It was actually a peaceful feeling, like your magic had settled and just wasn't needed.

A large smile spread across your face, tiny fangs resting on your lower lip as you closed your eyes and focused inward.

You had a baby! Yours and Sans baby! It was tiny, so very tiny, but inside you could sense a soul that felt different from your own.

Sans...

You scramble to your bedroom where you had left your cell phone on the night stand, snatching it up and calling Sans. He picked up on the first ring.

"______?" You could hear Alphys in the background, speaking to Mettaton; "did you need me to pick something up?"

You inhale, words failing you for a moment.

"I...We..." You calm down and breathe out slowly; "Sans, I can't use my magic."

There was a beat of silence and then you heard footsteps hurrying up the steps and Sans was in the room suddenly, breathing hard and staring at you with wide sockets. His cell phone was still flipped open and it fell from his grasp; forgotten.  
Wordlessly, the skeleton reached out to hold you close; leaning his forehead against yours and closing his eyes.

His breathing became deep and steady. Smiling; you mirror his action and focused on where you had sensed the soul. It must have alerted Sans, because he gasped suddenly, fingertips brushing your lower tummy.

"i can...feel them," he murmured and his voice had a tremor that caused your eyes to open. There were glowing tears streaming down his cheek bones, his breath hitching.

Oh no, what was wrong??

"Sans...?" You question gently, cupping a wet cheek. He is shaking with choked sobs and you watch him with concerned eyes.

"i...i never thought..." His deep voice caught, "that i could be...so...happy. that it was possible to feel this happy, ever."

Your heart melted and you berated yourself for worrying that he had changed his mind. Sans' tears were happy ones. You smile, feeling warm tears pool in your eyes.

"i...we're...fuck..." His voice is ragged, overcome with emotion, "i am going to be a dad. their soul feels..."

Sans is unable to speak anymore and merely holds you close, teeth gently pressing to your lips in a 'kiss'. You bask in this moment with him for what seems like forever and then you suddenly pull back.

"We need to tell my family right away!" You tell him, bouncing on the balls on your feet in happiness. Sans' pupils were shining so brightly and his mouth moved into an excited grin.

"we should, before tori threatens to kill me. or burn my house down....among other things..."

Laughing you take his hand and sit on the bed, ready to set up a meeting place for everyone to get together. This was definitely more of a face-to-face conversation situation, rather than a phone call.


	25. Chapter 24

**Summary for the Chapter:**

> Okay, you guys got me. I will provide the link to the rough sketch of the baby; keep in mind that the colors and placement of the armor/exoskeleton is not true; just proof of concept. Basically, since you have Toriel's genes, your monster genes that you pass on is more goat monster and Sans' skeleton monster genes form as sort of an internal/external armored look. You are, of course, free to make up your own ideas/changes.
> 
> http://sta.sh/0nl0xgy01fy
> 
> Sorry about the short chapter! I have horrible insomnia usually, but for some reason; I slept for nearly two days?? As such, I am horrible on making domestic chapters, so there will probably only be two more of the main story and then an epilogue. I already have another Sans x Reader story lined up, so no worries!

Monsters sure did make a point to be punctual, it wasn't even three hours later that everyone had assembled in the cabin you shared with Sans and Papyrus. Toriel, Asgore, Asriel, Frisk, Undyne, Alphys, Mettaton and Papyrus were all chatting away happily with each other in the living room. Of everyone gathered, only Toriel, Alphys and Undyne seemed to know what may be coming; as they were desperately trying to capture your gaze. Your father and siblings seemed to be half asleep.

"Okay, ya nerds; I can't take the waiting anymore," Undyne said softly, "are you going to make us wait all night??"

Everyone's attention rested on yourself and Sans and he beamed suddenly, the skeleton looked like he couldn't help himself anymore.

"______ and i are expecting a baby." He murmured. Asgore, Asriel and Frisk were suddenly wide awake as the room was filled with elated cries. Toriel lifted you off of your feet and was cradling you like a child, causing you to flush in response.

"Oh, my child! I am so happy for you!" Toriel told you with a wide grin and her amethyst eyes fell on a shell-shocked Asgore, "we are going to be grandparents, 'Gore."

Since it seemed like their father wasn't going to answer them, Asriel and Frisk were tugging at Toriel's purple robes.

-Baby?- Frisk signed as Asriel stared up at you in askance.

"You both are going to have a niece or nephew." You told them with a smile and Toriel sat you down, happy tears in her eyes.

"And Sans is the daddy?" Asriel questioned.

You nodded and looked over to your soul mate to see Papyrus looking between you in confusion.

"I DON'T GET IT, SANS!" Papyrus said over the joyful cries of everyone and Sans grinned up at his younger brother.

"we made a babybones together, pap," he said patiently, "you are going to be an uncle."

Papyrus frowned at Sans and then slowly looked between you.

It was quite apparent when the taller skeleton finally realized what this was all about.

"_______ IS EXPECTING A BABYBONES???"

Undyne and Alphys cracked up laughing at his delayed understanding.

"yes, bro," Sans said patiently, wrapping an arm around you as you shook with suppressed laughter.

"AND I AM GOING TO BE AN UNCLE???"

"Yes," you confirmed once you had your breath back. His eye sockets filled with dazzled sparkles.

"I WILL BE THE BEST UNCLE EVER. I PRO-" he broke off when he saw Frisk signing at him, "NO! I SHALL BE THE BEST, FRISK! NOT YOU!"

"Oh dear..." Toriel murmured with a fond smile as the two got into an argument with each other.

Sans' bony fingers tangled with yours as you simply allowed the happiness in the room wash over you.


	26. Chapter 25

**Summary for the Chapter:**

> One more main chapter and then an epilogue. Then, Continuity will be finished. *sigh* I really don't want to see it end, but I have so many more Sans to share with you guys!!!
> 
> So if you want to add on to this fanfic with your own work, please do so. ^^

It was hard to breathe through the fire rampaging through your body; your exhausted eyes peeling open to take in your soul mate as he ravaged your body. Sans had the sense of mind to move you both to a stream before you were both helpless to your monster instincts. Words completely failed Sans as he growled lowly; one teal eye boring into your face as he intentionally focused magic so that his cock would swell and grow; stretching you impossibly wider.

You moan helplessly; clawing at him as he released once more inside. It was probably by virtue of your magic and the water nearby that you didn't die. You had sworn over and over until you could only cling helplessly through your heat to Sans that you would die.

But you didn't.

"hey..."

Moaning softly; you open your eyes to take in your dim bedroom that you shared with Sans.

Oh... You had been dreaming. You breathe a soft moan through your parted lips and seek out your soul mate; who is resting between your parted thighs; gently easing you through your dream induced orgasm with teasing phalanges.

There is a gentleness to the white spots of light in his sockets as he takes in your flushed face, his free hand resting gently on the substantial swell of your pregnant stomach. You had been extremely self conscious early in the pregnancy about your growing belly, but Sans had all but wiped that notion away.

He always seemed to want to touch your growing child and the softness of your skin there, his expression openly awestruck and happy when he looked up to meet your eyes.

How could you possibly fight against that??

"dreaming about the heat, again?" He questioned gently; taking the glass of water from the nightstand and offering it to you. Smiling gratefully; you sipped on the cold liquid and sighed, not even embarrassed anymore.

"Yeah, it's been more often than not, lately;" you murmur and Sans gets comfortable next to you, his hand rubbing gentle circles into the tender, swelled flesh.

It had been eight months and you had been certain you would never make it this far. You had known your magic would be inaccessible but you hadn't known the hell it would wreak on you from the inside out. Your mother had assured you that everything was fine when your temperature and emotions got out of hand. 

When you had hit really close to that searing temperature to your heat cycle; half of the dishes exploded in the kitchen when you grew angry. Sans' had stared at you with wide eye sockets and held your hand throughout your emotional outburst.

Which...you recalled with a frown; had made you even more angry. Tears bit your vision and you shuddered.

"babe, what's the matter?" The skeleton questioned patiently.

"How have you not run screaming in the other direction?" You asked with a watery smile, which he returned warmly.

"simple. i love you." He pressed his teeth gently to your cheek in a tender kiss and you laughed.

"i love you too, but you know what i meant." You reprimanded.

His deep chuckle did amazing things to your heart, "also simple. your parents told me what to expect."

"But I have been horrible to you!" You insist and he hushed you.

"you are nurturing our baby and keeping yourself going; i can't imagine anything harder." Sans answered with a gentle look.

"How about reliving timelines over and over?" 

He considered this; "maybe it is up there with that. but i can deal with mood swings, princess. you were responsible for saving me from that fate."

You smile gently.

"I am so glad that we were able to make it here. To this."

Living on the surface, experiencing all of the new things life had to offer. Having your new, intact monster soul and through that, able to feel the solid connection you and Sans had.

All of that new happiness when you had been certain you both were going to cease to exist.

"yeah..." Sans murmured, staring up at you with half closed sockets.

You consider going back to sleep but Sans is suddenly sitting upright, tension in his expression.

"What's wrong?" You question in a tight voice and he gently placed a hand over your left eye.

It was radiating a soft teal.

"Oh..."

Your magic was coming back.

That meant...

"hold tight, i will get Alphys and alert your parents." Sans murmured, holding your hand for a moment before blinking from existence.

You take deep, calming breathes. It was fine. Sans would be back in no time; it was better that he had reacted quickly. It hadn't been three minutes before your soul mate is back; steadying Alphys with a nervous expression.

She muttered some colorful things about space and time, and sleep before fixing her glasses. She beamed brightly at your condition.

"At least he is great on reaction time, here ______. G-Get comfortable." She is fixing the blankets and pillows around you. You are still able to move, but can feel tension gathering in your body.

"Toriel and Asgore?" Alphys asked Sans gently as he pulled a chair close to your side of the bed and tangled his bony fingers in yours.

His left eye socket was blazing with light, his magic reacting in sympathy with yours.

"they are on their way. pap is expecting them and i told him not to come in." His expression is tense, searching your face as you wince.

"A-And you made sure to shield this room with your magic?"

Sans turned his full attention on her and frowned, "of course." He deadpanned and you laughed through your rising discomfort.

Alphys seemed more nervous than either of you.

....Which you supposed was a fair thing. If Sans hadn't put protective measures on this room; the house, the property and anyone on it would be crushed to dust from the intensity of your magic during labor.

She chuckled, sweating lightly.

"A-Are you ready for your baby, _______?" The dinosaur asked with a timid smile and you manage to nod.

You would be okay.

This was fine.

At least, you thought it was until the first backlash of magic struck you.


	27. Chapter 26

**Summary for the Chapter:**

> This is the last chapter of Continuity. There will be a tiny epilogue coming up, as well as a link to my new Sans x Reader story.
> 
> Thank you so much, for everyone who commented and left kudos, to newcomers, people who have been reading since the start and to those I corrupted. Thank you. I was so anxious in writing this and you all made it so worth-while.
> 
> If anyone wants to add onto this 'verse, you have my permission to expand on it. There is not a sequel planned; but who knows. I really do want to explore some new things.
> 
> Keep being amazing, sinners. <3

This was definitely not okay! Why was it that you only seem to grasp the basic of warnings about these things? Physically; you just felt pressure and 'pushing' seemed to hurt a bit. But your magic and your soul felt the most stressed. The pain was radiating from the room being too charged from your magic.

And anything that had to do with your soul made you have pretty horrible flashbacks of your time with Gaster.

Sans was leaned in close, holding your hand and murmuring gently in your ear when you were lost in the past. Alphys would have to stop trying to coach you to do certain things with your magic and she sighed.

"Sans, this is taking too long; we may have to just cut the b-bab-" Her voice died in her throat when the skeleton glared at her; one eye blazing with magic.

"she and the baby are fine," he murmured with narrowed eye sockets, "their souls aren't in trouble, but if you try anything; you will be."

You whimper and his attention returned to you after staring the scientist down. He nuzzled his cheekbone lightly against yours in a loving gesture as you search his expression.

"Is the baby really okay?" You pant, wincing as your magic buzzed against the wall loudly.

"you are both fine," he whispered, closing his eye sockets, "i will know immediately if something goes wrong."

"When...will it end?" Toriel had told you that magic had a way of working wonders for a new life if allowed to flow freely; but letting gravity magic have free reign like this was taxing you. Sans seemed more worried about you than in his preventative measures; which said quite a lot of his magical abilities to be certain.

"usually when your magic peaks; much like a heat cycle, but it comes in a short burst," he smiles at your groan, "a very short burst. but you have to push to get there; in both ways."

You whine in complaint. Not getting a heat cycle was one of the only upsides of being pregnant.

But you didn't want Alphys to cut you open. Not only would that deliver damage but you were pretty sure that Sans would possibly kill her in his current protective state. Even though monsters were created from compassion and hope; they sure did have a feral side.

"Ca-Can you help me?" You whisper to your soul mate; struggling into a sitting position that was only achieved when Sans physically held you up. Exhausted, you naturally wanted to slid down into a laying position. Your magic hummed, potent, through his bones but it would not ever harm him.

Gritting your teeth in a sound that made Sans wince; you focus on pushing and allowing your magic that terrifying and wild reign. You had been fighting the levels on instinct. Your heat cycle was the only instance you had used so much magic before now. 

Fighting wasn't something you did at all above ground and the (SAVE ALL) function had used your human soul entirely.

This was painful and raw; sobbing as your muscles convulse. Sans moved into a better position to hold you; one teal eye taking in your expression in concern. You knew that you were trying to rush it.

Maybe if you just stop fighting and let go...

You just wanted the pain to end and to have your child.

Alphys gasped as your magic drug across the air quite near her and the buzzing was growing into a vicious thing. If Sans wasn't shielding her and the room; you would've likely dug a crater so far.

A small touch on your thigh makes you jerk in surprise and Sans' sockets narrow in warning at Alphys, a growl rumbling in his rib cage.

"S-Sorry! I wanted to say, k-keep that u-up!" She smiled toothily at your expression, "t-that is g-g-good!"

Really? You blink, sweat running down your face. You had been trying too hard? Sans is holding you up and you just give in; allowing the gravity magic free roam. The buzzing and pressure seemed violent.

And suddenly; the air went so silent that it frightened you. It felt like something snapped along with the magic because suddenly you felt no pressure and much less...full? Sans is absolutely still beside you.

A tiny but breathy wail warbled in the dead air and Alphys is laughing; drying something of both red blood and teal fluid.

Your baby... 

Alphys carefully wrapped the squirming bundle in the soft blanket Toriel had knitted, "it-it's a girl!"

Tears swim in your vision as your new daughter continues to fuss and cry and you reach out both hands desperately. Carefully; the infant is eased into your arms and you sit back. Sans suddenly seems to remember how to function and he peers anxiously over your shoulder.

Large amethyst eyes filled with glowing blue tears blink up at you as your daughter silently takes in your face. Her body is covered with the softest white fluff and her ears looked ridiculously touchable. She has barely noticable blunt horns, but you were sure they would grow. 

Some of her body was covered with pearly looking bone that you were certain ran true of her internal frame. Her ribs and visible knuckles are outside of her body. It doesn't alarm you; seeing as who her father was.

She smells so warm and new..

"she's beautiful," Sans murmured breathlessly in your ear and your daughter's gaze moved to the monster in response to his deep voice.

There was a long pause as the infant took in the skeleton's face before a fanged smile pulled at her mouth, boned paws reaching for him.

"Uh oh, looks like she is going to be a Daddy's girl," you laugh and Sans looked star struck as you offered him his daughter. Gently, the skeleton held the infant to his chest and to your delight; the whites in his eyes were now tiny teal hearts. 

It was barely noticeable, but insanely cute.

"did we decide on a name for a baby girl?" Sans asked you quietly; gently running a fingertip across the exposed bone. It was slightly soft; like Papyrus' has been.

"Well, we found out that you and Papyrus had fonts up here, so..." You tilt your head, "how about Arial?"

He hummed lightly and then smiled at his daughter before raising his gaze to look at you.

"thank you..._______," there were tears threatening, "i can't...thank you."

You chuckle tiredly and notice Alphys just staring at you two in happy bliss. She would likely draw a manga or something from this.

"Can you tell our family that we are okay?" You question and she snapped out of it.

"O-oh! Yes, of course! Get some rest!" She opened the door and shot you both a thumbs up, "everyone will be eager to meet Arial."

Arial was cooing, tiny hand closed around one of Sans' fingers as you laid down next to him.

"This...has been an adventure," you murmur and he chuckles in response.

"She has only been born, get ready for another one."

Raising a child sounded more difficult than saving the Underground and changing species but, you didn't mind the thought of it at all...


	28. End

**Summary for the Chapter:**

> Short and sweet; the ride hasn't been without turbulence but you enjoy where it has taken you.
> 
> Here is the link to my new work: http://archiveofourown.org/works/5682910
> 
> I hope you continue to support me. If not; at the very least; keep sinning. Sans needs your love. <3

“Uncle Papy-roos!” Arial demanded, holding out her tiny arms and jumping up and down for the tall skeleton’s attention, “I can’t see!” She complained. You glance around your soul mate and nudge his shoulder; drawing his attention from the fireworks going off in the starry sky.

 

He huffs a deep laugh and Arial squeals with delight as his gravity magic surrounds and embraces her tiny form, “yeah, papy-roos; should pay more attention to my princess.”

 

“DADDY!” She screams, wriggling in the magic and reaching for him. He chuckles and winked at her before he levitated her on Papyrus’ shoulders. 

 

The skeleton immediately notices, “PRINCESS! HOW DID YOU COME TO BE ON MY SHOULDERS?! DID YOU JUMP??”

 

She giggled and held onto the estatic skeleton’s head. Sans rolled his eyes fondly, squeezing your hand as you kiss his grin tenderly.

 

“how old is she getting now?” The colors of the light show reflect off of his skull.

 

“This is her fourth New Year’s celebration, Sans.” You say with a laugh, glancing at the rest of your family. Frisk and Asriel were burning sparklers together with Asgore and Toriel watching.

 

Alphys and Undyne were a little too wrapped up in each other to notice the celestial display.

 

The fireworks were sailing above the shadow of Mt. Ebott. You…and Sans had come such a long way. Monsterkind was free now. You and Sans were free.  
And Arial had been born. You had never noticed you didn’t age until recently. Sans had explained adult monsters only aged for as long as their young relied on their magic. So you had many, many, many years to look forward to.

 

Silently, you close your eyes; sensing the teal soul within you; pulsing with your firm connection to the skeleton that held your hand; your daughter’s happy laughter ringing throughout the winter air.

 

Somehow, despite it all; you can’t help but smile.

 

What a beautiful night…

**Author's Note:**

> Ah~ My first Undertale fic as well as my first work in which the romantic dynamic is heterosexual. ^^;; I hope that you guys like it! Please let me know as I am unsure if this will be well received. I am going to Skele-Hell for this.

**Works inspired by this one:**

  * [A Reader's Continuity](https://archiveofourown.org/works/5669800) by [Athesia](https://archiveofourown.org/users/Athesia/pseuds/Athesia)




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